Downgrade from Sequoia to Sonoma leaves Sequoia partition on disk

Greetings. I needed to downgrade from Sequoia to Sonoma but after the downgrade there's still a disk partition that contains the Sequoia OS. I want to remove it so I can utilize that disk space but I've not been able to figure how. I've searched this forum and online with no results. The downgrade process was done using a bootable volume.

How can I (safely) remove the Sequoia partition? Thanks!

Please see attached screen shots.

Disk utility screenshot showing the unused Sequoia partition:

Disk utility screenshot showing the unused Sonoma partition:

And on the desktop two root drives appear: