How to remove someone off will/deed?

My mom and dad are separated but are on good terms (prob don't matter), and they bought a house and land when they were married. The land and house are all paid off. A few years ago they both agreed to put the land in my brother and mine's name, however I still believe they are on the land/house deed as well.

Now the tricky part. We just found out kinda recently about my brother being bad off on drugs and other things associated with that. We are still helping him try to get over this, but my mom and dad would like to remove him from the land/house deed so that he couldn't get it taken from the LEO or use the land to bail himself out of jail, etc. Well my mom talked to the person who put me and my brother on the deed, and they said that they couldn't remove him from the deed. Does this sound right? I mean my mom and dad both agree to it and were the original ones to buy and pay for everything. Only recently have we been added to it, but you would think that the ones to add someone, could remove them as well.

So we are looking for some advice on how to handle this and suggestions on taking the next step. I was wondering if the only way to remove him from the deed, was to get him to sign something to that effect.