I also problems with removing the bridge, so, to start fresh again, I decided to do a factory reset via the commandline.
(because I couldn't remove the bridge, I couldn't logon to the web interface anymore)
Anyway:
/etc/init.d/factoryreset start
gives:
cp: cannot stat '/var/lib/misc/luserdb': No such file or directory
./factoryreset: line 46: /usr/bin/astp: Nu such file or directory
And after that the systems stays the way it was before, no reset took place.