Time Machine mirrored by Trash folder

Time Machine backups should never manually be moved to the trash. The only option now, is to completely Erase the Time Machine backup drive and start new Time Machine backups.

FWIW the Time Machine backups are protected in later macOS versions, so that they can not be altered or moved to the trash.

To Erase an External storage device (TM or not) with macOS Disk Utility.

Select "Show All Devices" then select and Erase the entire External storage device.

see > Erase and reformat a storage device in Disk Utility on Mac - Apple Support

This all looks absolutely right

You can delete files from an External Drive and place them in the Trash

You can eject the drive and the Trash will appear as empty

You can reattach the same drive again and Presto - the Trash is full again

All normal behaviours

You see, the files in the Trash are Still ON the External Drive awaiting for user to Empty the Trash

In this specific case, I am 100% with the assessment of @den.thed

Cherry picked Time Machine Backup Snapshot to delete ?

Not a good idea as this may even corrupt the index files TM Backup uses

In so doing, ALL the TM Backup Snapshot maybe compromised to the extent All will be lost

davidra wrote:

If I attach the hard drive and the deleted files are in the trash, then I format the disk, will those files in the trash disappear, or will they be stuck in the trash folder?

If you erase and format the external TM hard drive, the TM backups will disappear from the trash.

davidra wrote:

Disk manager is not letting me erase the disk. It can't be unmounted because it's in use. The trash folder did end up with the old files as expected. How can I reformat it in this situation?

Ignore my last post. I managed to erase the disk....there was a finder window open.

Good work! I'm glad to hear that you were able to work thru it and solve the original problem.

Had what seemed a very similar issue yesterday. My drive was in use as a backup drive with Time Machine. But it kept appearing to have errors/failures which I could not resolve. Sometimes OK; sometimes not.

Could not erase on my M4 mini.

Took it across to my M1 MBP which also couldn't erase.

Plugged it into my old Windows machine and was able to delete the big partition.

Back to M4 mini, set up new APFS partition from Disk Utility. Appears to be OK now. But it did demand a password (or whatever they called it) for the drive - which I don't remember having to use when I first formatted it. And it would have been known to the M1 mini system I restored from in order to set up my M4 mini. So surely should have been somewhere inside the cloned system?

I feel lucky to have a Windows machine. Which is a very rare feeling.

Thank you.

That is what I tried. And it would not erase. Even on a different machine and with the volume unmounted

Point blank refusal.