When trying to delete an item, there may be several reasons as to why you are not able to do so. Deleting an item depends on whether the item is attached to a Proposal, Order or an Invoice.
1. An item attached to a Proposal will not be allowed to delete if a "payment" is posted toward the Proposal.
2. An item attached to an Order will not be allowed to be deleted.
3. If an item is attached with an Invoice, it cannot be deleted. If you must delete the item, you may void the Invoice first then afterwards you will be able to delete the item.