erase Catalina volume, keep Big Sur test?

[breegenie]

How do I delete the Catalina volume and (only) its data? Search brings up moving back to Catalina from Big Sur, but I want the opposite - I want to keep Big Sur's volume and dump Catalina.

I have a MBP 13 2020 running a Catalina (migrated some data from Sierra) and a test partition with Big Sur 11.1 so I could test my company's new VPN process for Big Sur.

I'm happily crash free in Big Sur - Catalina has an issue with kernel panic crashes after unplugging from Thunderbolt Display, and graphics card kernel panics caused by Photos stuck in a never-ending photoanalysisd process that is still occurring when I boot into it.

 

[DeltaMac]

If you simply want to remove the Catalina volumes - those are the Macintosh, and Macintosh-Data volumes.
You know how to get into your Disk Utility, so just right click on each of those volumes, and choose "Delete APFS volume" from the menu.
That will remove both volumes immediately.
Make a backup of that Macintosh HD first, so you have "a way back", just in case something happens to your Big Sur system. You still have it named as "BigSurTest", which doesn't make me too confident that you are going to stay with that...
But, if you are sure, go for it - don't look back.

 

[breegenie]

Thank you - I deleted the Macintosh HD and data volumes. Some other articles made me worry because it was all in the same container.

BigSurTest has been renamed and appears to be functioning normally, I did have a Time Machine backup of both, just to be safe. Now to get my files imported from a Sierra Time Machine backup - my iMac died so I didn't have time to settle into Catalina.