So I'm in the process of fixing up an old Power Mac Dual G4 MDD for my Dad. I'm installing all the software he'll use, setting all the pref panes, etc... I've turned on Time Machine, and when I give him the computer for Xmas I'd like for there to not be remnants of this setting up process. Right before I shut off the computer for the last time before giving it to him, how would I delete all of the old backups and just leave the "current" backup?