How to completely reset WP permissions

Hi,

I wanted to make some custom permissions, I used WP Front permissions plugin but the free version didnt allow me to customize what I needed.
I removed the plugin but all the changes are made were saved.
I reinstalled it and used “reset to default”, but it had no affect.
Now my permissions are bugged and messed up. I have 2 new permissions, subscriber has some awkward effects on posts, contributors cannot contribute anymore etc

How can I completely reset all permissions to the initial roles ? To work just like if WP would be new installed?

Worth to mention: the website is live for over 3 years and had over 1000 accounts…