Issuing the command sudo rm -rf /opt/xen-orchestra will remove the bulk of it.

@kevdog I've fixed the scripts on Github. You can issue the following commands
from your XO console to remove the incorrect symlink --

cd /usr/local/lib/node_modules/
sudo unlink xo-server-auth-github

The symlink will be properly recreated the next time you update the VM.

P.S. I believe your issue with the hanging backups is unrelated, so you may want to dig further in the logs to see if you can identify the cause.