Delete all attributes in one record except name and username.

Not really knowing what it is you are trying to do but...

What you are doing is

DELETE FROM users WHERE id = $userId;

What you need to to is set the other fields to null if they are nullable.

$row = Model::find($id);
$row->column1 = null;
$row->column2 = null;
$row->update();

I think you try like this

$user = Test::where('id', 14)->where('username', 'like', '%dd%')->first();
$user->update(['username' => null]);

What Tray2 said. When you are using a delete action, it just deletes the record, but you still need to manually set the fields to null. You can do it like this as well:

$row = Model::find($id);
$row->update(['column1' => null, 'column2' => null]);
$row->delete();

So first you update the columns and then you delete the record.

You could also set a custom delete method in your model, where you perform the above actions, so you don't have to put it in the controller for example. Or you could also use a model observer:

    public static function boot ()
    {
        parent::boot();

        self::deleting(function ($model) {

            $model->update(['column1' => null, 'column2' => null]);
            $model->delete();

        });
    }

Or perhaps even something like:

    public static function boot ()
    {
        parent::boot();

        self::deleted(function ($model) {

            $model->update(['column1' => null, 'column2' => null]);

        });
    }

Not tested, but just something you could try, whatever suits your needs.