Because it is based on the same code set as XP Pro. They make some minor changes, and slap the name HOME on it.

#1 - don't delete the built in Administrator account. You're asking for trouble if you do.
#2 - don't delete the support account either, just disable it.
#3 - delete that funky user account with the MMC, it's about the easiest way. Right click My Computer -> Manage. In the Computer Management window that opens, expand the tree object (press the +) for Local Users and Groups. Select Users, and the right panel should populate with all users. Simply right click and delete it from there.