It is easy to make a proper removal tool if you have access to a drill press. Do this instead of the socket approach. Here is a photo of one that I made out of 1/4" plate steel:
The 4 bolts are attached (with nuts) to the shaft coupling. The 1/2" bolt in the center is tightened (the plated is threaded for it) and pushes the shaft out of it. This took about 20 minutes to make.