I don't think it can be removed or at least it was not meant to be removed. Tom Woods once told me to pump grease until you see clean grease spill out.
It should just unscrew so you can pull (if it's not frozen) the splines apart. You may have to persuade it with a hammer if the splines are stiff/frozen.
This one was tricky as there is not much information on the web. It has a sheet metal outer case and a rubber seal inside that when you press it onto the slip yoke, the rubber latches into the groove on the end of the yoke.
Anyways, I cut it off in order to make an educated decision on weather or not to rebuild this shaft. I'm glad I did the extra effort because the plastic on the splines was coming off on several.