Removing the chuck from an AEG battery drill is the same as removing the chuck from any other brand of drill. You just have to put an Allen wrench into the mouth of the chuck and use a normal wrench to rotate the chuck attachment nut. This will require some upper body strength but should be manageable by most people. If you want to attach a new chuck you can just reverse the process and have a fully functional power drill.
Turn the AEG battery drill off by putting the direction selector in neutral. Remove the battery by depressing the two buttons on each side of the battery at the bottom of the handle.
Insert a stout Allen wrench into the mouth of the chuck. The bigger the Allen wrench the better, as smaller Allen wrenches could become bent by the levels of torque involved in this process. Tighten the chuck mouth by rotating the control surface clockwise while holding the drill handle steady.
Slip a wrench onto the nut that lies directly behind the chuck. It is OK to lay the drill down at this point. You will need both hands free. Hold the wrench on the nut steady while you grasp the Allen wrench and rotate it counterclockwise. You will need to take the Allen wrench out and reinsert it into the chuck periodically so that is does not hit the work top.
Pull the chuck off the AEG drill motor axle once it becomes loose. You have now removed the chuck and can attach a new one at your leisure.