how to "reset" Simple Custom CSS plugin

Hi there,

my problem is a bit tricky:

1.) Simple Custom CSS was installed, Changes in CSS were made. Everything was fine so far.

2.) Accidently Simple Custom CSS was deinstalled (unnoticed!). But all changes in CSS were still persisting (how that?) All CSS changes are still working!

3.) After noticing that Simple Custom CSS was missing in the plugin list some weeks later (some more changes in the CSS had to be done), Simple Custom CSS was installed (the second time).

4.) Everything in the Frontend still looks fine (like it was on 1.)), but further changes via Simple Custom CSS won’t work anymore.

Is there any possibility to “reset” the plugin, or are there any other solutions to fix the problem, to make Simple Custom CSS work properly again?

Thank you very much in advance for any hints and clues!!!

T.C.

https://wordpress.org/plugins/simple-custom-css/

P.S. I use Gridstack as Theme. Today I installed Gridstack-Child-Theme. Changes in Child-Theme-CSS won’t work also 🙁

How can I get rid of the information Simple Custom CSS has written in the system?

Thanks a lot for every kind of help!