To unassign or delete items to vendor in inventory, follow the steps given below:
Step 1:
Select the Inventory module and then select the Vendor Item Mapping under Vendors and
Contracts menu.
(Inventory-->Vendors and Contracts-->Vendor Item Mapping)
Step 2:
Select the Company Name and click on View/Delete Assigned Vendor Items then select the
items accordingly and click on Unassign Items.