We did it a few years back... First step is to make sure that you're covered by PLIA (I think that's the acronym). It's the state insurance that covers you if the tank has leaked. Depending on how old it is, it leaked most likely.
In our situation, our tank had leaked a little and PLIA covered the clean up cost and the tank disposal, recommended a provider (can't remember their name), and we just paid for the tank to be taken out of the ground.
Call the state PLIA people and ask a lot of questions. They were really helpful.