I recently had my 2002 A4 B6 repainted. I have an intense dislike of masking tape, so I thought it was better to remove everything, including the chrome (on my car, black on others?) surround that goes from the front of the "A" pillar above the doors, then wraps round the small rear 1/4 window.
After much searching on various VAG forums, I couldn't really find a documented method for doing this - apparently (and I can't vouch for the truth of this), Audi recommend breaking the rear 1/4 windows...
Anyway, after fiddling about, here's how I did it (if anybody's interested):
DISCLAIMER: You follow these instructions at your own risk. No liability for damage or injury will be accepted etc etc.
CAUTION: If you're not doing this to repaint the car, protect the paint around the areas your working on with thick tape!
TOOLS REQUIRED: A selection of blunt trim removal tools (right-angled), a blunt scraper, Scotchbrite, T-Cut (or similar) polish, double-sided adhesive tape (1mm thick, about 12mm wide), 1/8" or 3.2mm diameter drill bit and electric drill, soft-faced hammer, about 20 or so 1/8" pop-rivets and a rivet gun, and plenty of patience. A capable assistant might be handy too.
1. The surround is in two parts - a polished (or black) alloy trim, and a flat, black plastic "weather" trim that you can see from underneath.
2. The black plastic piece can be peeled off, starting at the front (bottom of the "A" pillar). It will curl up as you do this, but don't worry about that. Be careful not to lose the two plastic locating pins that will fall out at this point. Notice that it's a snap fit into a pair of "rails" in the alloy bit (important for step 9).
3. Once it's off, you'll see that the alloy bit is pop-riveted and stuck (with double-sided tape) to the car. Drill off the heads of the rivets (use a 1/8" or 3.2mm drill, and do just enough to remove the heads). This will release the trim from the bottom of the "A" pillar to the top of the rear 1/4 window, but you'll have to peel it off because of the sticky tape.
4. The remaining piece which curls around the rear 1/4 window is retained by some spring clips which "grab" it from behind. You can pry this off using a suitable right-angled trim removal tool (the hard plastic kind), combined with some swearing.
5. That's it - any stuck rivet bodies can be punched through the holes using a 1/8" punch. They'll go inside the upper body seam and presumably fall down into the sills in the future. If you're very good with a hoover, you might get them out...
6. Remove all traces of the old double-sided sticky tape from the back of the alloy piece (I used a blunt scraper, followed by Scotchbrite), and replace with new tape. Use T-cut to clean off any adhesive residue from the car body.
7. To refit things, use the two plastic locating pins to position the alloy piece on the body push it home onto the body. Once the main section is stuck on, the piece around the rear 1/4 window "just" presses into the clips on the body.
* CAUTION - make sure you pull the window rubber out over the top of the surround.
8. Install new pop-rivets to fully retain the main piece.
9. The black strip which curl'd up when you removed it can now be re-installed. It locates at the bottom of the "A" pillar on a small tab in the alloy bit. Starting here, push the lip that's behind the inner edge of the plastic into the rail (that's the edge nearest the car body), then tap firmly with a soft-faced hammer to snap the outer edge into place. Work your way up the "A" pillar and along the roof line.
* NOTE - when you get close to the rear 1/4 window, you'll see the black plastic strip goes behind the surround, so you have to slide it in there first, before you finish snapping the last few inches of the plastic into place.
Hope this is useful for somebody...