Old back ups
I would like to get rid of some old, old, back ups on my external hard drive and keep the more recent ones.
MacBook Pro, macOS High Sierra (10.13.6)
The old Pondini instructions are still helpful.
http://www.baligu.com/pondini/TM/12.html
It is really hard to recover significant amounts of disk space.. Especially if you have upgraded the OS a couple of times and kept using the same backup drive.. You will do much better buying a new drive and starting a fresh round of backups.. hold the old backups for a few months until you have a sufficiently large history.. then you can use the old disk again by erasing the backup if you really need to.. IMHO drives are cheap enough I would keep it as archive in the bottom of a fireproof filing cabinet for a couple of years.. after all.. pictures are irreplaceable.. and bad stuff happens.