The bmgr wipe command doesn't work. Also disabling the BackupManager didn't help removing the backup sets. Is there any alternative way to remove those sets?
Is there any option for that in the Google account settings on the web?
You can go to the website google dashboard
After you log in with your backup account, you can see your backups under the "Android" section.
At the end of this section, you have an option to erase backup data