It would perhaps be better to send such things as POST, so that the user ID's don't come in the URL

So, set up a route in your routes.php file that looks like:

Route::post('admin/delete', 'AdminController@deleteMany');

In your POST request, send an extra parameter that contains the user ID's in the form 1,2,3,4,... And in the controller, you simply have to take that parameter using Input::get() and then use the explode() function to get an array with all the ID's.

Watch out... Never trust user input and perform a good validation on the array to be sure you only have numbers in it (very important!)

Hope that this answers your question...