end dat to absence type and plan

We want to replace an Absence Plan and type based on Hours by Plan based on dates. We have created a new plan and type but now want to put an End Dat to previous type and plan to avoid employees to schedule an absence after December 31th.

When trying to put an end date an error message is displayed: "You can't delete this master record because a matching detailed record exists"

What are the steps to put an end date to Type and Plan?