Wow!
After reading through the different threads you sent me, the one where someone said you have to highlight all of the old landscape’s streaming proxies as well worked!
As you can see here, after I highlighted everything that was related to the particular landscape that I wanted to delete, ONLY THEN was I successfully able to delete it!
Now, I also read where some people were having a problem with the old landscape re-appearing after they saved & exited UE5.
I didn’t have that issue.
I saved & exited, and then when I returned, it was still gone!
Thank you, SupportiveEntity!
Justin