Website not rendering and giving error

I tried to install The Signup Password plugin on the site through the WPMU DEV Dashboard. Now I am getting an error message "The Signup Password plugin is only compatible with WordPress Multisite."

Since I am not able to access my dashboard it is not possible for me to delete this plugin. Worse, I am not able to see the plugin in the wp-content/plugin directory and hence can't delete the file from there as well.

The website in not rendering and the error that is being displayed is "The Signup Password plugin is only compatible with WordPress Multisite."

Help me.

best regards

Sanjeev