Once you create a Release, you may wish to delete it. Perhaps the Release was created with incorrect information, as part of the wrong Title. Whatever the reason, a Release can be deleted so long as it doesn't have any Deliverables yet. (If it does have one or more Deliverables, it can't be deleted, but can be marked inactive.)
Go to the Releases screen and click on the name of the Release you want to delete.
Select the "Tools" tab.
Click the "Delete Release" button.
Note that once a Release has been deleted, it can't be restored.