Nothing.
We cannot process any instructions with respect to a membership via email. This includes, but is not limited to, requests to cancel, to accept payments, to register, renew, or transfer domains, to disable content, or to remove anything.
Email is not secure. Anyone who knows your email address can send an email that appears to be from you. Some people don't even bother using your email address when pretending to be you. We routinely receive emailed requests to do stuff that clearly aren't from the member. But the scary ones are the ones that look like they are from the member but turn out not to be.
Even when we're pretty sure you're you and we believe there would be little risk in doing so, we cannot process an email request. After all, we could be wrong. And even if we're not, we also need to take reasonable steps to protect not only you, but also ourselves.
So, on our system, the way you prove you're you is to log in with your member login name and password (and, optionally, a two-factor device).
If you need help logging on, check out the Login section of our FAQ.
If you need our help with something else, the best way to obtain it is via the support tab of our member site.
If you have a subscription membership, you can submit requests via email if you want, but you'll still have to click a link, log in, and confirm that the message really came from you. (Which basically copies it into our support system as if you had submitted it from our site.) That does introduce delays, so you'll generally get faster response if you send such requests directly from the support tab. Please note the option for individual email-based support is only available to subscription members. Baseline members should check the support tab for community support and self-support options.