How to edit default policy allow the owner of a team to delete messages in Microsoft Teams?

Step 1: Sign into Office 365 admin portal via https://portal.office.com

Step 2: Click on Admin from the left pane and navigate to All admin center > Teams.

Step 3: Click on Messaging policies on the left pane.

Step 4: Click on the default policy or the policy you want to edit from the list of policies.

Step 5: Enable the Owners can delete sent messages option.

Step 6: Click Save.