Changing from Email verification to Admin approval not being accepted

When I initially set it up, my client requested the member registration to use the Email Verication method. However, he has changed his mind and now wants to manually approve registrations.

No problem, I just change the pull down menu from Email verification to Admin, and hit save.

The problem is this change in settings is not being applied and the email with the verification link is still going out so the registration process hasn’t actually changed. Every other setting I change gets applied so it’s not a permissions issue blocking all changes, it’s just this one issue that’s not changing.

Is there some way I can force it? Is there a cache I can clear or a database table I can manually alter? (I’m not running any caching plugins)