I’ve been there, installed a plugin and then the worst happens. The white screen with an error code across the top. The admin area is always affected as well. Can’t login.
Delete the plugin from the directories folder. Now, not everyone has a cPanel. It depends on your hosting provider.
Because of how simple & easy it is to have a cPanel, I’ve only used hosting companies that use cPanels.
A list of companies I have used can be found here.
Once you have logged in, head over to the File Manager (picture #1). Once that loads you will see a list of folders on the left-hand column.
Click on the folder called public_html (picture #2) and then click the folder called wp-content.
After you click wp-content the last step is to find the folder called plugins (picture #3).
Click that folder and locate the plugin that caused the issue.
I typically just rename it and add (broke) at the end of the name this also disables the plugin. Alternatively, you can just delete the plugin folder.
If you still need help, I am available.