Problem/Confusion about merging branches and "modify/delete" Conflicts

Question

Here's the hierarchy of the 3 Branches in this story:

  "master" branch
         |
   JohnReedAvery
         |
       Birdy

Earlier today, I finished a couple of scripts in the "Birdy" branch, and I wanted to merge "Birdy" (those 2 scripts) into "JohnReedAvery", for the EVENTUALLY purpose of merging "JohnReedAvery" (those 2 scripts) into "master". But I did not merge "JohnReedAvery" into "master" YET. Rather, I wanted to test the "git rm" feature, for completely removing one or more files (commits) from a Branch's entire {whatever word I should use here} --meaning: from the local working-dir and (in effect) from staging and from the local repo (commit) AND from the remote repo (GitLab / origin). I seemed to completely succeed in completely deleting the 2 previously-merged commits (those 2 scripts) from the "JohnReedAvery" branch. BUT THEN I wanted to merge Birdy back into "JohnReedAvery" again, so that I could proceed to a test Merge Request for merging "JohnReedAvery" into "master.

HERE'S THE PROBLEM:
When I attempt to again merge "Birdy" into "JohnReedAvery", I am getting the following types of error messages:

CONFLICT (modify/delete): JohnReedAvery/Birdy/File01 deleted in HEAD and modified in Birdy.
Version Birdy of JohnReedAvery/Birdy/File01 left in tree.  

I get this for each of the 2 scripts in Birdy that I am attempting to merge (again) into "JohnReedAvery". When I first saw this error, it was for only 1 of the two files and that one was the only one that "JohnReedAvery" (branch) was able to see in the "Birdy" subdir. (It had not been able to see it after I completely all of the "git rm" and "commit" and "push" steps to delete all that stuff. This one showed up ONLY AFTER this partly-failed attempt to merge this 2nd time.) So, I guessed that it wanted me to do another "git rm" on that same file (which I had successfully done a few min before), and that seemed to work: the "JohnReedAvery" (branch) view, of that file, disappeared.

But now I'm getting the above error on EACH of the 2 scripts when I am again attempting, yet again, the merge from "Birdy" into "JohnReedAvery" and I do not have any idea of what it thinks is wrong.

Can you all give me some idea of what's wrong here and how I fix it?

Thanks!