You cannot remove them – you will need to replace the power by another one. Open Kanai’s cube, click on the glove, and then select anything else that you have already extracted the power from. There are 3 or 4 panels for armour… so a lot to chose from.
If you haven’t extracted the power of another armour item… you’re stuck with those gloves until you do. Armour item includes everything except weapons, shields, rings and amulets.
The answer to that part of your post is already in the post you are replying to: