Managing Backup Files

Libre office 25.8 Win 10/64
I’ve located the backup files directory and see a large number of files that I have no more need of. Question, is there an option in Libre Office for managing these backup files, specifically to delete backup files with some user selectable parameters such as date?

Secondly, are the backup files .PDF’s by default? They can not be opened by a PDF reader, but can be opened and saved in LibreOffice DRAW.

Please advise.