To permanently close down your Outlook.com email account, you need to close your Microsoft account. And, when you close your Microsoft account, your email and contacts are deleted from our servers and can't be recovered. The email address is made available 60 days after you close the account and can then be used by someone else. If you use your Microsoft account with other Microsoft services, you will no longer be able to access them.
Get more information on the effects of closing a Microsoft account.
Close your Microsoft account
Note: Remember when you follow the steps mentioned below, you'd be permanently shutting down your Microsoft account. All your emails and contacts will be deleted from the server. To simply log out from your email account, go to your profile picture at the top right corner and choose Sign out.
Go to Close my account.
Note: If you are asked to sign in or verify your account, follow the instructions.
Check that the page shows the correct Microsoft account, and then click Next.
Read the list and check the boxes to acknowledge you’ve read each item.
In the Select a reason drop-down list, choose the reason you're closing the account.
Click Mark account for closure.