How to obsolete Inventory inspection plan where Item is not there

Summary:

We have encountered a scenario, where we had created Inventory Inspection plans and approved them. But there was a change in UOM because of which the Item numbers are now disappeared from the plan.

The problem now is all those items for which UOM was changed had respective plans in approved status. Now since the Items have been disassociated from plans it is not even allowing to obsolete them.

We tried creating new plans and were able to create for same Item, Org but using different name and it is getting approved.

Please suggest how to obsolete the earlier ones as it is not allowing anything from Obsolete, even version change.