Switch to REST for the user deletion

src/app/user.service.ts

@@ -276,14 +276,12 @@ export class UserService {
   }
 
   public deleteUser() {
-    return this.http.delete('/backend/api/delete_user').pipe(
+    return this.http.delete('/rest/user').pipe(
       catchError(this.handleError(true, "Error deleting user")),
     ).subscribe(
-      (data: {deleted: boolean}) => {
-        if (data && data.deleted) {
+      _ => {
           this.user$.next(undefined);
           this.snackBar.open('Deleted user from server');
-        }
       },
       this.logErrorAndFetch,
     );