There is no such thing as an uninstaller for MagicWB. Replacing the icons either by hand or by replacing via the 3.1 disks is one thing.
It's certainly not the best looking solution as you use Bloodwych's ClassicWB package with other iconset, so replacing the stock 3.1 icons will look rather crappy.
Imho you have 3 options:
1. Reinstall your ClassicWB pack from scratch backing up whatever you want from your current setup
2. Setup the ClassicWB pack of your choice in WinUAE and transfer only the icons to your Amiga replacing the MagicWB ones.
3. If you like the MagicWB set but you use lo-res, you can use Aminet's SmallMagic pack (and Bloodwych has a lot of these on his low-end versions as well), replacing the current original MagicWB icon packs which will look just fine even in lo-res.
