How to prevent a Team’s members from editing 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 Teams on the left pane and then click Manage teams.

Step 4: Click on a team from the list and then click Edit on the top-right.

Step 5: Scroll down to Team members can edit sent messages option under Coversations section and turn it off.

Step 6: Click Apply.