Just screws off. I usually grab the stem just below the crown with needle nose pliers and twist. Be careful though, if you are shortening the stem, you must not screw up those threads. When shortening the stem, don't be too cavalier. Make your first with room for error. Install it, then take a bit more off. For my first cut, I used the dremel cutting disk. For subsequent alterations I used the cutting disk as a grinder, taking tiny amounts off each time. Also, you may have to shorten the tube slightly (I used a fine file). Hope this helps!
If done properly, the results will be perfect. Below are my two POs, one stripped and shortened, and the other not!