I had a lot of trouble finding how to do this and finally figured it:

  • Login to ovirt admin console
  • Go to Storage>Domains
  • In the Domain Name column click on the name of your domain
  • Click Data Center tab then click the maintenance button
  • Takes a minute or so but once that is done click detach
  • Go back to Storage>Domains and click Remove

References:

https://lists.ovirt.org/pipermail/users/2013-April/013858.html