Saves?

In the game, there is a little icon to the left under each save name. You can hover over it, and it will tell you the slot number. Write down the numbers that correspond with the saves you want to delete (or in your case you want to keep), and delete the others. Also, there will be ver0, ver4 etc. Those are the older versions of each save. I usually get them mixed up but I think 4 is the most recent. Someone else may have to correct me on that. To make sure you can also look at the dates of which version file was created.

Edit to clarify: The icon is similar to the copy icon in Windows, if I remember correctly. I'm not near my computer so I can't show you a pic.