How can I delete my backup files on my C: drive?

I currently have PE2026 running from an external hard drive.  However, I didn’t think about where to have the backup files stored, and now I have run out of space on my C: drive.

1.  How can I change my settings for where the backup files will go in the future?  I have a USB 3.0 with 512G I can store my backups on.                                                                                                       
2. Where are the current backup files on my C: drive?  I need to free up memory, and I also want to make sure that I only remove the backup files and not remove any of the actual system operating files.

I greatly appreciate your help!  If there is someplace I can find this information, I would be happy to do this myself, but I haven’t found the information online.  :)