Yes, I've used it myself, although that was only for the remote locking bit. The bit you're having trouble with is the immobiliser, the car turning over but not firing is because the immobiliser is still enabled.
I'm sure there's a way to delete the other keys but not the master, you can't reprogram the master itself. Although I don't think that having the maximum number of keys is likely to be your problem, otherwise you wouldn't have been able to program the remote locking.
I would suggest to keep trying in case you're just not quite doing that bit right.