Now that I've upgraded to macOS26, I want to delete all my previous backups by deleting the current db and reinstall o a new backup so my Time Machine backups will install a new db startng with my new MacOS26 I don't need to restore from them so it should work.
[Re-Titled by Moderator]
Original Title: Deleting Time Machine Backups
Mac mini (M4)
Sounds like you just want to start a fresh TM backup. In System Settings > General > Time Machine, select the backup destination in the list of disks then click the (–) button at the bottom to Forget the destination. You can then click the (+) button, add the drive and select the option to start a new backup.
Between the forget and add steps above, open Applications > Utilities > Disk Utility, select the top level of the drive, then click Erase. Format as GUID, APFS, not encrypted (let TM handle the encryption when you add the disk as a destination), and when that's done go back to system settings and add the disk (you might be prompted by macOS to use it for TM after the reformatting, and that works, too).
Sounds like you just want to start a fresh TM backup. In System Settings > General > Time Machine, select the backup destination in the list of disks then click the (–) button at the bottom to Forget the destination. You can then click the (+) button, add the drive and select the option to start a new backup.
Between the forget and add steps above, open Applications > Utilities > Disk Utility, select the top level of the drive, then click Erase. Format as GUID, APFS, not encrypted (let TM handle the encryption when you add the disk as a destination), and when that's done go back to system settings and add the disk (you might be prompted by macOS to use it for TM after the reformatting, and that works, too).
How old is is your current Time Machine backup drive...?
If it is more than 2 or 3 years old, then it's probably a good idea to replace it.
To best answer your question:
Option 1) Erase the current Time Machine drive using Disk Utility and start new backups for the new Mac.
see > Erase and reformat a storage device in Disk Utility on Mac - Apple Support
Option 2) Get and setup a new external drive for the new Mac, then erase and repurpose the old external drive.
Deleting Time Machine Backups
