Cisco ASA 5505: resetting to factory defaults

I’m having problems getting this ASA 5505 device to actually reset to factory defaults. I did the:

devicename>en
devicename#conf t
devicename(config)#config factory-default

Once I do this, it goes through the entire process, and most of it looks like it’s been reset to default… except that I still have a password configured?!?! I try to do a:

devicename(config)#no enable password

But it’s requesting a specific level and will not allow a delete of level 15 password. Anyone have any thoughts? I’m trying to figure this thing out, am running out of time for playing/learning and need to reset it to start from scratch once more.

Any thoughts/assistance are sincerely appreciated!!!