Removing a bottle cap without damaging it is easy. Simply pry around the edges of the cap with a flat head screw driver. Try to pry evenly the whole way around. The cap should come off easily.
DO NOT USE A BOTTLE OPENER!!! IT WILL DESTROY THE CAP!!!
<< IF YOU USE THIS YOU WILL DESTROY THE CAP!
Some lamps have a plastic plug underneath the bottle cap. This can be removed by pulling on the sides until the vacuum is released.
Putting the cap back on:
Some people use bench cappers, but I prefer hose clamps. They cost less than a dollar and give a very tight seal.
Screw caps are the easiest to remove, simple unscrew them by hand. Some of these caps can be on very tightly and it can help to wrap rubber bands around the cap for a better grip. Sometimes these caps will crack due to their age when taken off. When putting the cap back on, pay careful attention to the rubber o-ring. It must be properly seated in the lid for a good seal. The cap should be snug, but if tightened very tight the cap will break.
To remove crimp caps you need a small screw driver to pry around the bottom lip. To put the cap back on, use the screw driver to press the cap back into its original shape. A pair of plyers can be used to give a tight seal on the cap, but this cannot be done several times or the cap will eventually get damaged.
Notice the wide neck? These are the only types of globes that a hand capper will work on.