XL Poles - To remove the cap from an XL pole (heavy duty) you have to remove the ball top and the swivels. The secret is to unscrew the ball topper. That allows you to remove the swivels (and the protective pole sleeve if it is located there). The top (smallest) swivel will be a little tight, just pull hard. The pole cap will come off the pole. You will probably want to save this especially if you are going to use it as a portable flag pole because it helps keep the inner sections from moving in and out. Put the swivels back on, largest on first.
XP Poles - To remove the cap (it is really a plug) from the XP series poles (extra heavy duty) pull on the ball topper and the swivels. Pull the plug out of the pole top. Put the swivels on over the inner pole, largest first. The top swivel will be tight, by design, to help keep it in place in stronger winds. After the swivels are on, put the ball back into the top of the inner pole. (Note: I like to put the plug in the top - after the swivels are on - and put the ball back through it, just for looks. When you do this you have to push the top swivel down a bit. Also, you don't have to worry about where you put it when you go to store the pole.