Laravel 5.1 Soft delete not working

I am using Laravel 5.1.

There is a model in my project for a table named scores as below:

<?php namespace App\Models;

use Illuminate\Database\Eloquent\SoftDeletes;

class Score extends BaseModel{

    use SoftDeletes;
    protected $dates = ['deleted_at'];
    public $timestamps=true;
    protected $table = 'scores';
    protected $fillable = array('user_id','score','numerator','denominator','created_at','updated_at','deleted_at');

    public function users() {
        return $this->belongsTo('User');
    }

}

I want to soft delete the records of this table. I am using eloquent as below:

$user_id = 10; 
$created_at = date('Y-m-d', strtotime($created_at));
$ps = Score::where('user_id', '=', $user_id)
            ->whereRaw('DATE_FORMAT(created_at,"%Y-%m-%d") = ?',array($created_at))
            ->delete();

But the records are getting hard deleted each time. Where am I making a mistake?

via Chebli Mohamed