Undo Administrator without a password

I have a personal laptop that I used to use at a business (Dell Inpiron 9200 running Vista Ultimate.) The IT guy set it up on the business network. The computer name is XXXXX1.mtd.local and the Domain is mtd.local.

Here's the problem; I no longer work at this company and the IT guy is long gone. Evidently he set himself up as Administrator and I am a user with administrative rights. I wanted to clean out most the business related stuff and not have to use the mtd login. I did set up a new user id and loaded all the files I want to keep into this profile. But, I can't get rid of the mtd stuff. I got so frustrated I even tried 'format C:'. I figured I'd just rebuild from scratch. I can't even do that. Permission was denied.

Is there anyway to undo what the MTD IT guy did so I can have complete control of my computer again without a password?

 

Okay, if I understand what you are saying, the root issue is that you cannot access administrative functions without knowing the password for the administrator account that was setup on your machine? Is that a fair interpretation of your issue?

 

I have administrative privileges as a User, but there are higher level privileges I don't have. There are files I can't delete - I get a notice I do have permission. I tried to reload Windows Vista and was told I could not load the program. I am assuming the IT guy set himself up with some higher level administrative authority. I'd like to eliminate this and have control of my computer.