If you no longer want to have another email account connected to Outlook.com, you can remove the connected account from Outlook.com. You only remove the connection between the other account and Outlook.com, not the email account or the email messages.
Note: If you want to permanently close your Outlook.com email account, you need to close your Microsoft account. When you close your Microsoft account, your email and contacts are deleted from our servers and can't be recovered. Learn more about closing your Outlook.com account.
What happens to my email when I remove a connected account?
Any email messages that were imported to Outlook.com will still be there after you disconnect the email account.
Tip: Before you remove a connected account from Outlook.com, we recommend that you sign in to the account via the original email provider and make sure your email messages are there. If they are there, after you remove your account you can delete all the account's email messages from Outlook.com and you'll still have a copy of them at your email provider. If they aren't there, after you remove the connected account, you might want to archive your email messages in a folder in Outlook.com instead of deleting them.
After you remove the account from Outlook.com, you can no longer send email from that account in Outlook.com.
Microsoft will be removing the ability to connect accounts to Outlook.com from May 10, 2021. If you remove it before that date, you will be unable to reconnect your account after that date.
To see your all your email accounts, calendars, and contacts in a combined inbox, download Outlook for iOS or Outlook for Android.
How to remove a connected account
Select Settings> View all Outlook settings > Sync email.
Under Manage your connected accounts, move the cursor over the account you want to remove and then select Delete .
After you remove the account from Outlook.com, you can delete email messages from the connected account.