Hi,
Have you created a sales order from BSO?
if yes then first delete the sales order which is associated with the BSO and then delete the BSO otherwise you won't be able to delete the BSO
if you don't want to delete the SO which was associated with BSO then simple ship and invoice the SO and then delete the BSO you would be able to do it
If my answer was helpful to you, please verify it so that other users know it worked. Thank you very much.
