Instructions
CAUTION: If you have made changes to items in Outlook while offline and those changes have not been synced to Microsoft 365, the changes will be lost when you remove the account from your Mac.
1) Open Microsoft Outlook if it is not already open.
2) In your Mac's menu bar, click Outlook and choose Preferences.
3) Click Accounts.
4) Click once on your TechMail account to select it. Then, in the bottom left-hand corner, click the minus sign (−).
5) Click Delete.
Outcome
Your TechMail account has been removed from Outlook for Mac.