Can't delete a few software licenses and the purchases orders for them.

Can't delete a few software licenses and the purchases orders for them.

I am unable to delete some software licenses which are connected to two closed purchase orders.  I would also like to delete both purchase orders.  No matter what I try, they simply will not delete.  They are not allocated to anything.  The two purchase order numbers are 2104 and 3001.  I would like to just delete the purchase orders and have both of the software licenses delete right along with them.  Is there any way to do that?
 
Thanks,
 
Tony