How do you sign out of someones mail account on the iphone?

my phone memory got reset and someone i know signed in to mail on my iphone to check their inbox, before i signed in. but i cant work out how to sign them back out now? =/
How do you sign out of someones mail account on the iphone?
Go to the settings icon and then to mail settings. From there you can remove the account from your mail app.
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