How to Close your Microsoft Outlook Account?
Follow the instructions on the page to make sure that your account is ready to be closed, and select 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.
Select Mark account for closure.
then sign out your outlook account
Select your account picture at the top of the screen.
Select Sign out.
For more details, visit : www.office.com/setup