Is there a way to delete Teams rooms chat messages via retention policy or any other way so that we can implement? if yes how to do it?

Hi @Vinod Survase

If I understood your question correctly, you would like to delete meeting chat (conversation) from a Teams room mailbox.

If there is any misunderstanding, please feel free to point out.

To me I suppose assigning a retention policy to the room mailbox should work for you, which would automatically delete (or archive as another option) items that reach a specified age (for example 1 week, 1 month or 1 year, etc.).
Related documentation on this topic: Retention tags and retention policies in Exchange Online

In short, you may need to:

1. access Microsoft Purview portal with an account which has permission, locate Data lifecycle management > Exchange (legacy) > MRM Retention policies
2. create custom retention tags (which controls how long a message remains in a mailbox and the action to be taken when the message reaches the specified retention age), or use the defaults ones if they can meet your needs
3. create a retention policy and add the retention tags you created
4. apply the retention policy to the room mailbox

Another option would be using the content search to manually delete the chat messages from the mailbox.

How to use Content Search and delete message: Search for and delete email messages

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