If you are trying to reset your account password then don't forget to check spam folder in your mailbox. Also Mark it as "not spam" or you won't be able to click on the link.
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It is simple. On top of your page, you will see an envelope in the middle. Click on that. Then click on start a new conversation. Enter my Username with starting with @. System will prompt. Click on it when it appears. Then DM. If you still have difficulty I will DM you.
Go to XF symbol on (top left) and keep scrolling down, till you come to ASK STAFF. There you can make your request. But remember you have to tell the reason why you want to close your account. They will help you.