Disassembling crank on a 2006 Trek Pilot 2.1 I'm trying to disassemble the crankset on my 2006 Trek Pilot 2.1; the bike has all OEM parts.
The crank is a Bontrager race crankset, which I'm to understand is a a rebranded Truvativ crank.
For a bottom bracket, it uses an SRAM Giga X Pipe (GXP).
The crank is a two-piece press-fit: it's a hollow tube press fit into the drive side, with ISIS splines on the non-drive side.
I'm trying to disassemble the crank and bottom bracket, so that I can clean the crank and crank spindle, and replace the bottom bracket.
I've unscrewed the GXP bearing cups and removed the crank from the frame, but there's this one last little component on the crank spindle that's keeping me from removing the rest of the GXP bottom bracket. I want to know how I should remove it so that I don't damage the spindle. I'm not sure what the part is, or if I'll need it for installing the new GXP bottom bracket.
Here's a shot showing the crank, spindle, and GXP bottom bracket as it is right now:

And here's a close-up of the spine, showing the collet I can't get off:

Yeah, I know it's a mess; that's why I'm trying to disassemble and clean everything and replace the GXP bottom bracket. That grease isn't grease anymore, it's more like metallic paste. Yuck.
I've already tried some light tap-work to try to get it off; it didn't budge, but I didn't go hard because I don't know if I'll damage it. Also, interestingly, it spins very freely in place.
In summary:

I'm replacing the GXP bottom bracket in whole, so I don't care about destroying it or old pieces that came out of it.
Do I need to preserve this collet? Did it come from the old GXP bottom bracket?
If I do need to preserve it, how do I get it off?

If I don't need it, I plan on trying to tap it off with screwdriver and a hammer; if that doesn't work, then cut it in half and split it open.

Also, since a few other people I had asked had been confused about this - the drive side of the spindle is permanently press-fit into the drive side bracket / crank arm assembly, since it's all one piece. Here's a picture:
I would try reinstalling the drive side and non drive side cups to the frame (to keep the spindle centered).  Then I would recommend a game of whack-a-mole on the spindle with a rubber mallet.  I have often had to remove a crankset this way.  A rubber mallet should be in pretty much any home mechanics tool kit.  The rubber mallet has almost no chance of damaging the spindle.  Provided you don't smash/dent your frame with it, it should be fine.

With the cups on tightly and nondrive side crank off, you may also try rocking the drive side crank arm back and forth some as you rubber mallet the spindle.