Inspect the shower door to determine if the towel rack is one solid piece or a bar with two hanging brackets on each side. Find the fasteners that secure the towel rack to the opposite side of the shower door. Pop off the protective caps that may cover the fastener heads using a slotted screw driver.
Loosen the fasteners using the appropriate tool. Match a slotted or Phillips screwdriver to the screw fastener heads and rotate the tool in a counterclockwise direction. Insert the tip of a small Allen wrench or a 6d nail into the hole located on the threaded knobs and turn the object in a counterclockwise direction.
Slide the towel rack, with or without brackets, out of the shower door slots to remove.
Assemble the new towel rack if it is not one solid piece. Slide the small inner tabs of the new towel rack through the shower door.
Secure the towel rack to the shower door using the fastener hardware that accompanied it.