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I'm trying to swap my stock hotend for an e3d, but I want to reuse my old bowden tube. However no matter what I try, I cannot unseat it from the PTF connector (either the hotend side or ezstruder side).

I've got channel locks that I'm using to compress the grey collar, and pliers that I'm using to try and grip the bowden with, but it holds fast. I've tried compressing and pushing, pushing and compressing, compressing and jiggling... nothing. Might as well be superglued.

The only advice I found was in this thread ( http://forum.seemecnc.com/viewtopic.php?f=54&t=2569 ) that said to push the bowden all the way first to relieve tension, then compress the collar, then pull - but that didn't help.

I don't want to cut this thing off, but I'm starting to think I have to. I've already damaged the bowden a little with the pliers. Any advice?

What your doing is push the collar and keep it held in while removing the tube is correct.
You shouldn't need pliers or any tools, just a guess but this is the problem.
Just use fingers to remove this, should be stuck. Only thing I can think of is you have melted this with the original hot end but kinda unlikely.

Instead of making yourself crazy step back and buy another tube, then the old one will come right out
You will then have an extra tube for the next machine!

The little fingers dig into the soft tube. I had a hard time with mine yesterday, I unscrewed it from the hot end, pushed the tube and collar in then pulled really hard. It came out

I wound up just giving up and cutting the stupid thing off. I tried hands, I tried tools, I tried it both in and out of the hotend... no success.

The e3d has a MUCH nicer push fit connector. That one actually lets go when it's supposed to.

I end up unscrewing the connector, never can get it out.