Scott Kelby posted a great tip on Lightroom Killer Tips a couple of days ago:
Go to your backups folder and delete the ones that are more than a couple of weeks old and free up all that extra space.
Yikes. I’ve had backups since 2012, so I didn’t hesitate to delete all but the last two, and freed up 3.3 GB of hard drive space in the process. I dig it!