The email details that show up in People are imported from your accounts and you can only add or remove them via Accounts. Go to the right hand side of the screen and bring up the Charms bar, scroll down to Settings and click on Accounts. That will show you which Accounts have been imported into People. For example you might have Hotmail, Gmail, Yahoo etc and any email addresses from those accounts will show in People. If you want to remove people you have to remove them from the account they are registered in. If you only have a Hotmail account then go to your browser and bring up mail.live.com and log in then go to the People tab using the drop down arrow and delete any contacts that you don't need from there.
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