add new function

dbHandler.go

@@ -366,3 +366,7 @@ func (dH *DBHandler) Exists(model any, relation string, key string, value any, l
 func (dH *DBHandler) AddRelation(model, relation any, relationName string) error {
 	return dH.db.Model(model).Association(relationName).Append(relation)
 }
+
+func (dH *DBHandler) DeleteRelation(model, relation any, relationName string) error {
+	return dH.db.Model(model).Association(relationName).Delete(relation)
+}