About This Mac Shows 43 GB of Backups, Disk Inventory X Shows 0 GB, Need to delete Backups
You may notice a difference in available space statistics between Disk Utility, Finder, and Get Info inspectors. This is expected and can be safely ignored. The Finder displays the available space on the disk without accounting for the local snapshots, because local snapshots will surrender their disk space if needed.


This also applies to Disk Inventory X. Local snapshots are hidden from view and you don't need to think about them. They will be deleted automatically when disk space drops below a certain percentage (20%, I believe).

You can enter Time Machine and remove the snapshots from there but you should not do this. They don't really take any space, since they give it up immediately when needed, and backups are a good thing.

More information: http://pondini.org/TM/30.html