The Classic's had SCSI drives, so you'd have to fine a PC with a SCSI card installed (not many). You best bet is to plug the hard drive into another computer that can handle two SCSI drives at once - boot up off the non-locked disk and then erase the locked disk. This may work.
Getting the hard drive out of your Classic II can be tricky. You need to have a 12" Torx-12 screw driver - and you have to be weary of the little Mac's internal moniter, which can give quite a shock (the hard drive is directly under the floppy which is under the moniter).