I checked the DIY for an easy way to remove Wheel roundels but couldn't find one. So I Took some pictures while I removed mine.
Small Jewelers screwdriver
Thin Cardboard (should be thinner than a dime)
Step 1. Cut a small piece of cardboard in a square. Ensure you have a good corner.
Step 2. Put the cardboard in-between the Roundel and the wheel. (this will protect your wheel better than a cloth)
Step 3. CAREFULLY wedge the screwdriver in-between the cardboard and the roundel. If you push it in too far you may scratch the inside of your wheel. (Circled on picture)
Step 4. Gently pry the roundel away from the rim. THIS WILL DENT THE INSIDE PLASTIC OF THE ROUNDEL.
Step. 5 Pull the roundel off and replace with your stock ones.
Lessons learned: Remove the roundels from the wheel before you put them on. This will save you about 10 minutes per wheel, and the risk of scratching your new ones.
FYI's these are 19" Breyton Race CS on 328i E92 stock height/suspension