Open Outlook on your Mac.
In the top menu bar, click Outlook → Preferences.
Select Accounts.
Click the + button in the bottom-left corner and choose New Account.
Sign in. The account will now appear beneath your primary account in the left column.
In your primary account, create any folders you need for organizing migrated messages.
Drag and drop emails from the old account into the new folders in your primary account.
Note: Outlook for Mac does not support moving entire folders—emails only.
Return to Outlook → Preferences → Accounts.
Select the old account.
Click the – button in the bottom-left corner to remove it.