how do I remove a user on my macBook Air?

First make sure you're logged into another Administrative user, then go to System Preferences and go to Users & Groups (Or Accounts on 10.6).

You can then click the lock symbol, and then select the other account you want to get rid of and click the - sign.

It will ask you to erase the data as well, and you'll want to choose to do that.

Thank you - this worked easily