OVERRIDE ADMINISTRATOR PASS WORD ON WINOW 98 & NT

I HAD BUY TWO OLD COMPUTER FROM SARASOTA COUNTY GOVERNMENT AUCTION TODAY. I WAS HOPING SOMEONE OUT THERE KNOW HOW TO OVERRIDE THE PASSWORD BECAUSE THE THEY (AUCTIONEERS)DID NOT GIVE ME ANY PASSWORD FOR THEM. THERE ARE NO BACK-UP DISC EITHER. I HAVE WINDOW 98 AND WINDOW NT. WHEN THE COMPUTER IS TURN ON, IT ASK FOR ME TO ENTER THE NETWORK PASSWORD FOR MICROSOFT NETWORKING. I JUST WANT TO TAKE OUT THE PASSWORD. THANK YOU FOR READING THIS AND WHAT EVER HELP YOU CAN PROVIDE.