Renamed backup now won’t upload

Hi,
I keep a couple of copies of my backups. I thought I’d rename one of the older ones to make life easier – but now I can’t upload it. It says it wasn’t created by WPVivid (it was).
Also, I would like to be able to delete a plugin which I suspect is causing a problem – I can’t access my site since sending a live link using that facility on Local by Flywheel this morning. The message I’m getting is ‘You do not currently have a Shield user session. Please login’ . I had Shield activated but hadn’t set it up yet, never had issues before.
I was thinking maybe I could remove it from the plugins folder, then rezip it & upload it again. Can you please advise best practise for doing that?
This site is not (well, was not) running live. I’ve spent months working on it and presentation is next week, so slightly panicked atm. When I say slightly, I mean total meltdown happening here. If I could reupload it without Shield, I’m seriously praying that would work.
I await any advice and would be omg so grateful for any suggestions!
Regards,
Marita