403 Error on Admin Login

I have used ITS for years and had it set up to use a custom slug for admin login, for example, https://www.mysite.com/site-login. Suddenly, it’s throwing a 403 error and I can’t access the admin section of my site. I’ve cleared cache, tried different browsers, tried using a vpn, searched the htaccess file for my IP which is not listed. I deleted all reference to ITS changes in the htaccess file and that just gave an ‘error’ message when I tried to access the admin login page. I looked in the wp-config file and can find no trace there of why I’m suddenly getting 403 So, I’m out of ideas. Anyone have a solution? Is there a way to disable ITS from ftp so I can access the Admin area of my site?