Changing my email address on my user account

On examining my user account, I find that my email address is one that I no longer use so I have decided to change it. The problem is, I don't see any easy to do this. Should I first delete the whole user account then add a new account with the correct email address or is there an easier way around it? By the way, does this action have an immediate effect or is there some delay before I can use it afterwards?

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