Recent versions of unity have an annoying habit of crapping useless packages into your project. When those packages inevitably have errors, this sort of thing happens. I have railed about it before.
Go into the package manager and remove crap you don’t need, like the entire test runner and collab and whatnot.
If you feel brave you can hand-edit the Packages/manifest.json file a lot faster than using the laggy package manager interface that only lets you remove one package at a time:
I’m sorry you’ve had this issue. Please consider using source control in order to guard and protect your hard-earned work.
Personally I use git because it is free and there are tons of tutorials out there to help you set it up.
As far as configuring Unity to play nice with git, keep this in mind:
https://discussions.unity.com/t/736093/3
Here’s how I use git in one of my games, Jetpack Kurt:
https://discussions.unity.com/t/807568/3
Using fine-grained source control as you work to refine your engineering:
https://discussions.unity.com/t/826718/2
Share/Sharing source code between projects:
https://discussions.unity.com/t/719810/2
Setting up the right .gitignore file:
https://discussions.unity.com/t/834885/5
Generally setting Unity up (includes above .gitignore concepts):