Added the ability to remove an MFA method

Includes testing to cover

app/Actions/ActivityType.php

@@ -52,4 +52,5 @@ class ActivityType
     const AUTH_REGISTER = 'auth_register';
 
     const MFA_SETUP_METHOD = 'mfa_setup_method';
+    const MFA_REMOVE_METHOD = 'mfa_remove_method';
 }

app/Auth/Access/Mfa/MfaValue.php

@@ -21,6 +21,14 @@ class MfaValue extends Model
     const METHOD_TOTP = 'totp';
     const METHOD_BACKUP_CODES = 'backup_codes';
 
+    /**
+     * Get all the MFA methods available.
+     */
+    public static function allMethods(): array
+    {
+        return [self::METHOD_TOTP, self::METHOD_BACKUP_CODES];
+    }
+
     /**
      * Upsert a new MFA value for the given user and method
      * using the provided value.

app/Http/Controllers/Auth/MfaController.php

@@ -2,6 +2,8 @@
 
 namespace BookStack\Http\Controllers\Auth;
 
+use BookStack\Actions\ActivityType;
+use BookStack\Auth\Access\Mfa\MfaValue;
 use BookStack\Http\Controllers\Controller;
 
 class MfaController extends Controller
@@ -18,4 +20,21 @@ class MfaController extends Controller
             'userMethods' => $userMethods,
         ]);
     }
+
+    /**
+     * Remove an MFA method for the current user.
+     * @throws \Exception
+     */
+    public function remove(string $method)
+    {
+        if (in_array($method, MfaValue::allMethods())) {
+            $value = user()->mfaValues()->where('method', '=', $method)->first();
+            if ($value) {
+                $value->delete();
+                $this->logActivity(ActivityType::MFA_REMOVE_METHOD, $method);
+            }
+        }
+
+        return redirect('/mfa/setup');
+    }
 }