Backstory:
I am running macOS Sierra and use TextEdit a lot. The problem is that I hate the Versions save schema that causes the universal Save As shortcut of CmdShiftS to instead create a copy of the document. I also hate how Auto-Save makes permanent changes to documents I don't want to modify when I'm tentatively modifying a work-in-progress. Since the introduction of these nuisance features in Lion I have always backed up and then replaced TextEdit.app with the legacy 1.6 version from Snow Leopard.
The problem:
Today when I tried to delete TextEdit.app from my Applications folder using this Terminal command
sudo rm -rf /Applications/TextEdit.app
I got this error
rm: TextEdit.app: Operation not permitted
I was surprised to find that I can't kill it, even with sudo.
How can I actually get rid of an application that is bundled with macOS?
What I've tried so far:
I followed the instructions in this article, but it didn't work. I also read this SE answer, which almost accomplishes the same solution by means of disabling Versions and Auto-Save, but then I don't get the benefit of legacy TextEdit's temporary backup saving feature. See the part in the answer stating "This effectively disables the old-style, pre-Lion autosaving completely".
So I think deleting the newer TextEdit v1.12 and replacing it with the legacy v1.6 is still the best option, however I can't get my system to delete it. Any help appreciated.