How to disable laravel 5.2 password bcrypt

Try extending SessionGuard and overriding function hasValidCredentials()

Create A file by name 'SessionGuardExtended' in App\CoreExtensions

use Illuminate\Auth\SessionGuard;
use Illuminate\Contracts\Auth\Authenticatable;

class SessionGuardExtended extends SessionGuard
{
    /**
     * Determine if the user matches the credentials.
     *
     * @param  mixed  $user
     * @param  array  $credentials
     * @return bool
     */
    protected function hasValidCredentials($user, $credentials)
    {
        return ! is_null($user) && $credentials['password'] == $user->getAuthPassword();
    }
}

Edit config/auth.php edit the driver and use sessionExtended

'web' => [
    'driver' => 'sessionExtended',
    'provider' => 'users',
],

In AppServiceProvider Write Code in boot function

/**
 * Bootstrap any application services.
 *
 * @return void
 */
public function boot()
{
    Auth::extend(
        'sessionExtended',
        function ($app) {
            $provider = new EloquentUserProvider($app['hash'], config('auth.providers.users.model'));
            return new SessionGuardExtended('sessionExtended', $provider, app()->make('session.store'), request());
        }
    );
}

Reference: Extending Laravel 5.2 SessionGuard