Installed 4.1 plugin on 4.2 and crashed the app, how do I go back to before installation of the plugin

I'm using the nop 4.2 without source code version, and try to use the PayPal Express plugin that is only updated to 4.1.
I made a terrible mistake here: I extracted the 4.1 folder out of the plugin zip, put into the plugin folder of nop, and modified the .json file and changed the 'supported version' from 4.10 to 4.20 manually. Then I went into the local plugin tab in administration and found it and clicked 'install'.
I now know I shouldn't have done this and this is a huge mistake, especially when I forgot to back up my site up before I do this risky experiment.
Please help...how can I roll back to the previous state which has the plugin now installed? I don't know any time travelers or time magician around me...
Or, is it possible to find the files that this PayPal Express plugin changed, and manually replace them with the files from original nop 4.2?
Any help is appreciated, thank you in advance (cry)

The current state of the site displays this error:
Internal Server Error
An error occurred while starting the application.
.NET Core 4.6.27414.05 X64 v4.0.0.0    |   Microsoft.AspNetCore.Hosting version 2.2.0-rtm-35687    |    Microsoft Windows 6.3.9600    |   Need help?


The plugin I messed up is https://www.nopcommerce.com/p/1149/paypal-express-payment-plugin-nopcommerce-team.aspx

Hello,

You can go to the ~/App_Data folder and find the plugins.json file and edit it. Inside you will find the system name of the plugin either in the "InstalledPluginNames" or in the "PluginNamesToInstall" array. You will need to remove it and restart your store and it should work.

If the plugin has a database it most likely has inserted tables into your database. When installing the 4.20 version of the plugin, it will most likely try to delete those tables before creating them again. But if you have any issues when installing the 4.20 version it will probably be due to this. In that case, you can just delete the tables the plugin has created in your database (if it has created any).

Note: Please make a backup of your database before doing anything. It is really dangerous performing any work to your store without a backup of your information.

Hope that helps!

Regards,
Anton

Delete the PayPal plugin folder.
Yes, you should also edit the plugins.json file as per above, but just deleting the folder should get you up again, since there won't be a 'bad' plugin to load.