how to permanently delete files?

[avz]

Hm...
different subject. OP was asking about snapshots made on system drive, those which are done always (even when TM is switched off) by system and "take up" space on main drive of the computer. NOT TM snapshots.
TM pruning and deleting of old records is different thing and while it mostly works, sometimes TM hangs and fails. I eventually gave up and once TM disk starts running out of space, I file it and keep as backup and get a new one. I use 8-10TB disks for ~4TB of running disks (1TB system + 4TB external for data which is also included in TM) and 8TB backup drive lasts few years before it actually fills up. Then I file it, get a new drive and go from there. These are all HFS formatted drives and in my experience they have tendency of failing due to file system issues after few years anyway. That filing system seems complicated and fragile.
Do not have experience with APFS TM drives yet.

Actually I believe that turning TM off or excluding the main drive from backup will stop the snapshots altogether(even manual).

 

[madrich]

Hm...
different subject. OP was asking about snapshots made on system drive, those which are done always (even when TM is switched off) by system and "take up" space on main drive of the computer. NOT TM snapshots.
TM pruning and deleting of old records is different thing and while it mostly works, sometimes TM hangs and fails. I eventually gave up and once TM disk starts running out of space, I file it and keep as backup and get a new one. I use 8-10TB disks for ~4TB of running disks (1TB system + 4TB external for data which is also included in TM) and 8TB backup drive lasts few years before it actually fills up. Then I file it, get a new drive and go from there. These are all HFS formatted drives and in my experience they have tendency of failing due to file system issues after few years anyway. That filing system seems complicated and fragile.
Do not have experience with APFS TM drives yet.

Thanks for the clarification. Somehow I thought the issue was intertwined with the TM (time capsule).
No I do not have experience with APFS on the TM disk yet. Besides my TM is old, but still works.