Hi Peter,
Greetings.
Thank you for raising your concern in this community.
If you have already archived what you need, the next step will be to
- remove your account
- Select Tools > Accounts.
- In the lower left of the Accounts dialog box, click the - sign to sign out or delete..
- clear the cache.
Go this location and remove the content of the outlook 15 profiles folder. It includes the differente outlook profiles data.
~/Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles
Outlook for Mac is a locally cached email client - Outlook | Microsoft Docs
Make sure to empty the delete items from the trash.
When restarting outlook, you may be asked to sign up using a previous account, you can choose add another account.
If you choose to unistall the app, please make sure to follow steps from this article Uninstall Office for Mac (microsoft.com), Download Microsoft Outlook for Mac for Office 365. from Official Microsoft Download Center
If you have further concern feel free to let me know.
I will be waiting for your feedback for further assistance.
Kind regards,
Mac