I apologize and thank them for trying it out. I tell them how to delete their account (or delete it for them if it's not easy). I tell them we just got starte

I apologize and thank them for trying it out. I tell them how to delete their account (or delete it for them if it's not easy). I tell them we just got started and ask: "Question: How can we improve the site such that you'd recommend it to your friends?" I thank them again for "giving us a shot". I sign the email as a cofounder of the site. So far the majority of deleters answer the questions and are very, very nice about it. The change in tone from "delete me" to their pleasant tone in the final response is great. I keep meaning to toy more with ~"We know you might not like the service, but here's a few free months (coupon code) you can give to your friends as our thanks for giving us a shot and providing great feedback."