It's possible to grind the clip off -- I'm speaking of the current version, whose clip is obviously a separate part, like this:

It takes a
very steady hand with a Dremel (not a bench grinder) to do it, lest you nick the metal nose cone. You can also remove the nose cone from the pen with an application of gentle heat and a little force from two pairs of section pliers, and then you can simply remove the "clip" that holds the clip in place and watch the clip drop off. You can resecure the nose cone with 2-part epoxy.
The two trapezoidal holes that the clip was installed through give the nose cone a cool appearance, sort of like one of the Rebellion's fighters from
Star Wars.