Solved! Go to Solution.
You can use NI's License Manager software to deactivate a license.
Open License Manager, found in the National Instruments startup directory.
Expand the tree on the left hand side to expose the item you wish to deactivate.
Right click, and deactivate.
*edit* In the case of hardware that has failed, you should be able to just go ahead and re-license on a new machine. However it couldn't hurt to send an email to NI Support indicating that you have done so.