My IPad was stolen and I used Locate Device to set password/lockout. Is there a way to be certain it is unusable?

You should:

1. Remote Lock the iPad (please remember the Passcode)

2. Leave a telephone number for him/her to contact you

3. Hope he or she will call you. If it is stolen, he or she is unlikely to call you.

This is on your laptop/computer

http://i1224.photobucket.com/albums/ee374/Diavonex/de65c51ed642230cf160dcd1ef5fd 8db_zps32a1e9dd.jpg

This will appear on your lost/stolen iPad

http://i1224.photobucket.com/albums/ee374/Diavonex/40ee3668d0b62b94887d4535b498e 9f2_zpsa722018c.jpg

He or She will not be able to use your iPad unless:

1. He/She break your Passcode

2. He/She wipe your iPad

Can not be made unusable. All the thief has to do is restore it.