Hey @d5,
Sorry to hear that!
To deactivate a plugin without having access to your WordPress admin area, you can follow WPBeginner’s guide (see the section “Manually Updating WordPress Plugins via FTP”). Alternatively, you can reach out to your hosting provider and they should be able to do this for you.
I’ve taken a look at your site, and it seems that you may be using WordPress version 4.6. WPForms Lite require WordPress version 4.9 or higher, so this may be contributing to the issue you see.
Once you have access to your WordPress admin area, please try updating WordPress to its latest version (currently this is 5.2.3).
When the WordPress version is updated, please try activating WPForms Lite again, and let me know how it goes?
Thanks ??