diff --git a/csharp/App/Backend/DataTypes/Methods/Session.cs b/csharp/App/Backend/DataTypes/Methods/Session.cs
index 5a3edd808..851a5fdca 100644
--- a/csharp/App/Backend/DataTypes/Methods/Session.cs
+++ b/csharp/App/Backend/DataTypes/Methods/Session.cs
@@ -375,7 +375,8 @@ public static class SessionMethods
         var emailOwner = Db.GetUserByEmail(editedUser.Email);
 
         return sessionUser.UserType != 0
-            && originalUser.Id != 0                                              // never edit the root user
+            && originalUser.Id != 0                                              // belt: legacy root-id sentinel
+            && originalUser.ParentId > 0                                         // never edit the main/root admin (parentless top user; ParentId<=0, Id NOT necessarily 0)
             && (sessionUser.UserType == 2 || sessionUser.HasAccessTo(originalUser)) // admins may edit any user
             && (emailOwner is null || emailOwner.Id == editedUser.Id)            // email not taken by another user
             && editedUser
@@ -402,8 +403,9 @@ public static class SessionMethods
         return sessionUser is not null
             && userToDelete is not null
             && sessionUser.UserType !=0
-            && userToDelete.Id != 0                  // never delete the root user
-            && userToDelete.Id != sessionUser.Id     // never self-delete (avoid lockout)
+            && userToDelete.Id != 0                   // belt: legacy root-id sentinel
+            && userToDelete.ParentId > 0              // never delete the main/root admin (the parentless top user; ParentId<=0, Id NOT necessarily 0)
+            && userToDelete.Id != sessionUser.Id      // never self-delete (avoid lockout)
             && (sessionUser.UserType == 2 || sessionUser.HasAccessTo(userToDelete)) // admins may delete any user
             && Db.Delete(userToDelete);
     }
diff --git a/typescript/frontend-marios2/src/content/dashboards/Users/User.tsx b/typescript/frontend-marios2/src/content/dashboards/Users/User.tsx
index 074c1c2bd..bec15752a 100644
--- a/typescript/frontend-marios2/src/content/dashboards/Users/User.tsx
+++ b/typescript/frontend-marios2/src/content/dashboards/Users/User.tsx
@@ -16,6 +16,7 @@ import {
   Tab,
   Tabs,
   TextField,
+  Tooltip,
   Typography,
   useTheme
 } from '@mui/material';
@@ -24,6 +25,7 @@ import Button from '@mui/material/Button';
 import axiosConfig from 'src/Resources/axiosConfig';
 import { InnovEnergyUser } from 'src/interfaces/UserTypes';
 import { TokenContext } from 'src/contexts/tokenContext';
+import { UserContext } from 'src/contexts/userContext';
 import { TabsContainerWrapper } from 'src/layouts/TabsContainerWrapper';
 import { FormattedMessage, useIntl } from 'react-intl';
 import UserAccess from '../ManageAccess/UserAccess';
@@ -43,6 +45,8 @@ function User(props: singleUserProps) {
   const [formValues, setFormValues] = useState(props.current_user);
   const tokencontext = useContext(TokenContext);
   const { removeToken } = tokencontext;
+  const userContext = useContext(UserContext);
+  const loggedInUser = userContext?.currentUser;
   const tabs = [
     { value: 'user', label: intl.formatMessage({ id: 'user' }) },
     { value: 'manage', label: intl.formatMessage({ id: 'accessManagement' }) }
@@ -161,6 +165,17 @@ function User(props: singleUserProps) {
 
   const isMobile = window.innerWidth <= 1490;
 
+  // Mirror the backend delete guards: the main/root admin (the parentless top
+  // user — parentId 0; its id is NOT necessarily 0) and your own account can
+  // never be deleted, so disable the button and explain why.
+  const isMainAdmin = formValues.parentId <= 0 || formValues.id === 0;
+  const deleteDisabledReason = isMainAdmin
+    ? intl.formatMessage({ id: 'cannotDeleteMainAdmin' })
+    : loggedInUser?.id === formValues.id
+    ? intl.formatMessage({ id: 'cannotDeleteSelf' })
+    : '';
+  const cannotDelete = deleteDisabledReason !== '';
+
   return (
     <>
       {openModalDeleteUser && (
@@ -350,18 +365,20 @@ function User(props: singleUserProps) {
                               defaultMessage="Apply Changes"
                             />
                           </Button>
-                          <Button
-                            variant="contained"
-                            onClick={handleDelete}
-                            sx={{
-                              marginLeft: '10px'
-                            }}
-                          >
-                            <FormattedMessage
-                              id="delete_user"
-                              defaultMessage="Delete User"
-                            />
-                          </Button>
+                          <Tooltip title={deleteDisabledReason}>
+                            <span style={{ marginLeft: '10px' }}>
+                              <Button
+                                variant="contained"
+                                onClick={handleDelete}
+                                disabled={cannotDelete}
+                              >
+                                <FormattedMessage
+                                  id="delete_user"
+                                  defaultMessage="Delete User"
+                                />
+                              </Button>
+                            </span>
+                          </Tooltip>
 
                           {loading && (
                             <CircularProgress
diff --git a/typescript/frontend-marios2/src/lang/de.json b/typescript/frontend-marios2/src/lang/de.json
index 45ebe5c3b..98e68932f 100644
--- a/typescript/frontend-marios2/src/lang/de.json
+++ b/typescript/frontend-marios2/src/lang/de.json
@@ -502,6 +502,8 @@
   "connectingToDevice": "Verbindung zum Gerät wird hergestellt...",
   "fetchingData": "Daten werden abgerufen...",
   "confirmDeleteUser": "Möchten Sie diesen Benutzer löschen?",
+  "cannotDeleteSelf": "Sie können Ihr eigenes Konto nicht löschen",
+  "cannotDeleteMainAdmin": "Das Hauptadministrator-Konto kann nicht gelöscht werden",
   "accessManagement": "Zugriffsverwaltung",
   "power": "Leistung",
   "voltage": "Spannung",
diff --git a/typescript/frontend-marios2/src/lang/en.json b/typescript/frontend-marios2/src/lang/en.json
index 699fabd95..947214b68 100644
--- a/typescript/frontend-marios2/src/lang/en.json
+++ b/typescript/frontend-marios2/src/lang/en.json
@@ -250,6 +250,8 @@
   "connectingToDevice": "Connecting to the device...",
   "fetchingData": "Fetching data...",
   "confirmDeleteUser": "Do you want to delete this user?",
+  "cannotDeleteSelf": "You cannot delete your own account",
+  "cannotDeleteMainAdmin": "The main admin account cannot be deleted",
   "accessManagement": "Access Management",
   "power": "Power",
   "voltage": "Voltage",
diff --git a/typescript/frontend-marios2/src/lang/fr.json b/typescript/frontend-marios2/src/lang/fr.json
index b07fbef50..7ac2b185a 100644
--- a/typescript/frontend-marios2/src/lang/fr.json
+++ b/typescript/frontend-marios2/src/lang/fr.json
@@ -502,6 +502,8 @@
   "connectingToDevice": "Connexion à l'appareil en cours...",
   "fetchingData": "Récupération des données...",
   "confirmDeleteUser": "Voulez-vous supprimer cet utilisateur ?",
+  "cannotDeleteSelf": "Vous ne pouvez pas supprimer votre propre compte",
+  "cannotDeleteMainAdmin": "Le compte de l'administrateur principal ne peut pas être supprimé",
   "accessManagement": "Gestion des accès",
   "power": "Puissance",
   "voltage": "Tension",
diff --git a/typescript/frontend-marios2/src/lang/it.json b/typescript/frontend-marios2/src/lang/it.json
index 2966bcf5d..84b4cf727 100644
--- a/typescript/frontend-marios2/src/lang/it.json
+++ b/typescript/frontend-marios2/src/lang/it.json
@@ -502,6 +502,8 @@
   "connectingToDevice": "Connessione al dispositivo in corso...",
   "fetchingData": "Recupero dati in corso...",
   "confirmDeleteUser": "Vuoi eliminare questo utente?",
+  "cannotDeleteSelf": "Non puoi eliminare il tuo account",
+  "cannotDeleteMainAdmin": "L'account dell'amministratore principale non può essere eliminato",
   "accessManagement": "Gestione accessi",
   "power": "Potenza",
   "voltage": "Tensione",