You need to open Phys. Inventory Journals. Press 'Functions->Calculate Inventory' for these items.
On 'Qty. (Phys. Inventory)' field put zero values. After that, post journal lines. All disputed inventory will be 0.
If you want prevent negative quantity in future, you must unmark 'Negative Invent. Adjmt. allowed' field in User Setup table for all users.
