Hi,
To remove the stock, you may go for physical inventory with MI01 and post the difference. You can not directly delete the material, since you have stock in system. Instead, you may remove the stock throug physical inventory, and then you may either flag the material for deletion in MM06 or block the material or you may create a new material status in OMS4 and assign to the material master.
In future, you may plan material archival to delete the material completely.
Regards,
AKPT