As an administrator, you can search for and remove conversations within Microsoft Teams which contain confidential or sensitive information.
In the event that one of the admins removes a message, you’ll be notified by a system message in place of the one that has been removed by the administrator that says This message has been deleted by an admin.

Frequently Asked Questions
CAN A Teams Admin delete posts?
The Team Owners in their Teams have the ability to delete messages and conversations in the Team Site. The terms messages and conversations can be used interchangeably. In the case of inappropriate messages, this can be used to remove that message as well as any accidental messages, incorrect messages, or anything else that does not belong there.
How do I stop Teams from deleting my messages?
– To turn on or off the editing, deleting, or switching options, you need to go to Teams Settings > Member > Permissions.
Why my Teams chat deleted automatically?
The retention policy will automatically delete the chats and channel messages within the organization when a retention policy is configured to have them deleted from the system. It will disappear from the Teams app if the messages are still visible there, and the users will be notified that they have been deleted as a result of a retention policy.
Are Microsoft Teams messages permanently deleted?
As a default, the information regarding chats, files, and channels on Teams is saved indefinitely. In the Microsoft 365 compliance center, you have the option to change your retention policies. You can set up a system to automatically delete messages from Teams chats or channels after a certain period of time.
Can Global Admin delete Teams chat?
There is only one person who is allowed to delete a chat in a Microsoft Team, which is the admin or supervisor. Members of the team have the ability to delete or edit only those messages that they themselves have sent.