Business wants to Inactivate Items in PeopleSoft Inventory, but they are not able to do so.

As per the discussion with Business:

1) They said that some items are created by mistake and duplicate to another item. Now they want to Inactivate such items.

2) There are many such items which are created by other users and being used at different places/modules but are duplicate to an existing item (considering that there are many users in our stock department)

Please advise how to inactivate such items which are created by mistake and are in use; although they are duplicate to other existing items.