Airport Time Capsule - Old Backups

Do you plan to upgrade to Big Sur soon?

A clean current backup is no bad thing.. I never tell people to erase backups without carefully thinking. But if everything is currently running well and nothing deleted recently that would need to be restored.. particularly photos/vids.. which are not recoverable easily. And you have not used the backup in ages.. then go ahead and do a quick erase.. it only takes a minute.

Then do backup of the Mac with the smallest drive.. when that is completed do backup of the other one.

It may still be better to erase again when Big Sur is installed but worry about that after.. having decent intact backup now is great.

Let me add a clone is also a very good thing. I don't trust Time Machine and have not done so for ages.

Too much.. I just shat in the nest and need to clear it out and start again.

What that notification is missing is..

Your old backup and entire history is going to be erased. Too bad!!

A Carbon Copy Cloner bootable clone to a USB drive can be worth its weight in gold.

It is free to use for a month.. one license covers all your home machines.

I have no links to the company.. just happy to recommend it.

It has never needed to wipe its backups.. TM did it every 2 months in the worst scenario..

Accessing the Airport Time Capsule through Finder and attempting to delete the redundant backup disk images does not work.

Actually that should work. Are you using main admin account?

What OS are your Macs using?

There are other ways.. via the terminal using command line..

https://discussions.apple.com/thread/8082925?answerId=32741303022#32741303022

or some apps but they seem to not work on Catalina.. no idea for Big Sur if you have upgraded.

Just search for file deletion apps.. the one I am thinking of is ???

or should I risk erasing everything and then running complete new backups for my MacBook and my wife's Mac Mini?

Personally I would do this. It is far superior method and for certain if you have upgraded to Big Sur a wipe of the TC disk is well worth it.

You can plug a USB mac formatted drive (same size as TC disk or larger) into the TC and archive the disk.. It will take all day for a full drive but then you can happily erase the TC knowing the backups are preserved. After a month or 6.. you can wipe this drive and use it for other things.

For later Mac OS it is no bad thing to create a bootable backup on a USB drive. I recommend Carbon Copy Cloner. They are still working on some issues with Big Sur but it is much easier to get back to working OS if something really bad happens when you have a clone.