Prune backup files

[pH3]

I do regular backups of the database, using the Ultimate's "Database Backup" tool. I always do a new backup, which means a new set of files is created.
That also means, after some time, I have a long set of different backup sets on my hard disk.

I would like to prune this list, i.e. to delete some of the sets.
How can I do it in Ultimate, so that Ultimate is "aware" of the fact that they have been deleted?

Thanks for your help!