I am trying to delete a couple of publication targets but am getting a warning saying This item is in use.

How can I find out what items have been published to this target? Or how can I force the deletion?

I have access to the database if needed but would rather do this through the GUI.

Update 1

The location of my publication targets no longer exist so unpublishing using the target fails.

Update 2

I was thinking about executing the following statements on my Content Manage Database to force Tridion into thinking items are unpublished. My PUBLICATION_TARGET_ID is 1. I'll try it on my test system first. Any reason why this would cause problems down the line?

UPDATE ITEM_STATES
SET STATE = 0
WHERE PUBLICATION_TARGET_ID = 1

UPDATE PUBLISH_STATES
SET STATE = 0
WHERE PUBLICATION_TARGET_ID = 1