@ManiV welcome to the Rockstor community.
I would first start with trying to get rid of the OwnCloud rockon. Since you’re new to Linux, I assume, you are not using an external client like PuTTY to log into the system (using the root user) for using the command line.
You could use the Shellinabox feature on Rockstor by clicking on the System Shell icon:
In order to execute the deletion you will need administrator access. So, as @phillxnet outlined here:
log in with the WebUI user when asked and then elevate to the root user from that account by
su -
it will ask for the password you created for the root user during the installation of Rockstor.
Once that’s taken care of continue with:
cd /opt/rockstor/
poetry run delete-rockon "OwnCloud"
this should take care of removing any remnants of the failed OwnCloud installation.
If you want to to still attempt to remove the Rock-on root share, make sure that the Rock-on service is turned off before you delete it.