Deletion of sampling procedure is not possible

Hi,

I am trying to delete a sampling procedure using QDV2 tcode. System issues message 'The sampling procedure cannot be deleted, as it is already used in an inspection plan'.

I checked in QDV6 tranaction 'Whereused list' for sampling procedure but ther eis no usage found.

I see in PLMK table . It displays assigned to a INspection Plan but deletion indicator is also on at the same time for this in Table PLMK..

How this samling procedure can be deleted?

Thanks

Manoj