I tried this out in my app. Instead of removing an email, I just changed it, so the original signed in email was no longer in the whitelist. I first changed the email in the google sheet. It can take up to a few minute for google to send the change to glide, but after a minute I hit the reload button in glide and it booted me out of the app on my phone within seconds. I then reset, signed back in, and tried by changing the email directly in the glide data editor. It took about 10 to 30 seconds for me to get booted out of the app on my phone. So I would say that it works quite well when you need to remove a user.