How do I delete another users Mac App Store Account?

About a year ago my brother-in-law was browsing through my MacBook Air and didn't like the fact that I hadn't upgraded to the newest OS X at the time. He then took it upon himself to purchase the OS X which was totally fine until a few weeks went by and I had some updates but could not update them. Turns out instead of just buying the new OS X under my iTunes id, he had signed me out and logged himself in so I needed his password to make the updates. I called my brother-in-law to let him know what had happened, and he ended up giving me the password so I could make updates. Unfortunately, he and my sister have since split and when I received an update a couple of days ago I couldn't make the updates as he has changed the password. I can't get a hold of him, and I really do not want to get his password again especially under the circumstances. Today I purchased the new OS X 10.8.5 and updated everything, but my App Store still shows I have 2 updates under his user id one for the iPhoto and the other for the Cloud Printer. Can someone please, please, please help me get this off!!! Thank you!