Can't "remove" a file just out of staged or unstaged changes list

I attempted to resolve a merge conflict. Once I had, I was left with a "x.txt.orig" file in unstaged changes list, and "x.txt" in staged changes list. ("x.txt" being the one with the resolved merge changes in it.)

So I wanted to delete the .orig file as I've done many times before. Now, however, I right-click x.txt.orig and select "Remove," and SourceTree says basically "OK, we will remove x.txt.orig AND x.txt". Looks to me like it is applying the selected command (Remove) to items in BOTH the staged and unstaged files list.

And there is no way that I can see to "unselect" files in either list, so that I could just have the one file I need.

The menu item needs to apply to ONLY the list (staged or unstaged) from which it was invoked.