How is the external drive formatted?
More than likely if that drive crashed the files you are trying to delete, and probably many more, are corrupted in some way or the drive permissions have changed to READ Only instead of Read + Write. You can delete anything if you don't have Write permissions on that drive.
That drive is in the trash. Any idea how to delete corrupted files in LR?
What do you mean the drive is in the trash? If the whole complete drive is in the trash just disconnect the drive and they should go away.
I suggest you post the question of how to remove objects from the trash over on the Apple Mac forums. There is a way to Empty the trash when things in it don't want to go away. But I forget which key or option you use to do that.