If you have a policy, and a rack attached to that policy, and rules configured to use that policy.
When you attempt to remove the policy, you get an error the rack isn't empty, as well as an error that it's used in rules, and the UI can hang to boot.
Since policy rules can only link to a single policy, and the rack is defined by the policy, I can see no reason why removing a policy shouldn't just remove the attached rules and rack in one click, albeit perhaps after a confirmation. It certainly at least shouldn't require several browser refreshes to get the rules removed manually, then remove all the rack applications from the policy, to finally be able to remove the policy.