update, delete entity relations

kernel/EntityRelation.php

@@ -203,4 +203,22 @@ class EntityRelation
 
         return [];
     }
+
+    public function deleteEntityRelationBySlug(string $slug, string $entity, Model $model): void
+    {
+        $moduleClass = $this->getAdditionalPropertyClassBySlug($slug);
+        if ($moduleClass and method_exists($moduleClass, "deleteItems")) {
+            $moduleClass->deleteItems($entity, $model);
+        }
+    }
+
+    public function deleteEntityRelation(string $entity, Model $model): void
+    {
+        $relations = $this->getEntityRelationsBySlug($entity);
+        if ($relations){
+            foreach ($relations as $relation){
+                $this->deleteEntityRelationBySlug($relation, $entity, $model);
+            }
+        }
+    }
 }