I had a look at removing the knee bolster this morning.
It is ultra-sonically welded (melded) to the lower dash panel.
Basically it's welded.
If you open the fuse panel, and peel back the corner of the felt type material, you will see there is a hole in the lower dash panel, where a spigot/boss protrudes through from the knee bolster - then they are melted together.
To remove the knee bolster you're going to have to break these melted points - I don't know how many there are.
This will leave holes in the lower dash panel - some will be out of sight - others may not be.
If you remove it - without cracking the lower dash panel, you're going to struggle re-attaching it at a later date. You'd have to screw into the bosses in the knee bolster, and use a large washer to clamp onto the inside of the lower dash panel.

The easiest way maybe to see if the lower dash panel is available without the knee bolster!