Can I delete rules from my custom approval plan?

Once a rule in an approval plan has been used in a order, it can no longer be deleted. This is because it would make prior approvals invalid and cause errors elsewhere in the system. The best options when you no longer wish to use an approval plan's rule that cannot be deleted are to either re-purpose it for a different approval rule or edit to something that will not be triggered by any orders in the system.  
To learn more about custom approval plans, see Ch. 064 Approval Plans.