Q: How to upgrade or erase drive: OS 8.6 with lost Macintosh Manager password

The Powerbook G3 Lombard with Power Logix 750 processor issued for use on my employer's network was stolen five years ago and, believe it or not, I just got it back. The current Systems Admin. says it's usless for work now and my boss says I can keep it. Here's the problem: it is running system 8.6 and has Macintosh Manager installed. It won't go to the Finder without a user or network admin password (I have no memory of one and the Systems Admin from that time is long gone and the current one has no clue what the passwork might have been ) and I can't even get it to startup from the CD drive with the original install disc (which I have) in order to erase it without entering the user/network admin password. Help! Bad enough it grew old while stolen but now I'm afraid it will be useless if I can't figure out how to get around the password or clean install OS X.