Hi all,
I did find a way to remove Rosetta again, but it involves the Recovery because the files are SIP Protected.

  1. Obtain a list of files/directories and LaunchAgents with: pkgutil --files com.apple.pkg.RosettaUpdateAuto

  2. Save them in a way that you can access them in the recovery

  3. Boot into recovery

  4. Make sure your disk is mounted

  5. delete the files from Disk

  6. reboot

I don't list the files here as the list might change with a later version of Rosetta.
I hope this helps everyone who is in the same Situation as I was.

Best Regards
Timo