How to update (edit) a Microsoft Teams message (thread or reply) inside a Teams channel via REST API

Simply No, Neither Update method nor Delete method

Two things which is available in Graph API, one is Post method and second is Get method. This is for messages inside a channel in Microsoft Teams.

Get channel message,

GET /teams/{id}/channels/{id}/messages/{id}

• Documentation: Get channel message

• GitHub: channel-get-message.md

Create chatMessage in a channel

POST /teams/{id}/channels/{id}/messages

• Documentation: Create chatMessage in a channel

• GitHub: channel-post-messages.md

If you want to update channel or calendar event then the API available for them.

• Patch channel PATCH /teams/{id}/channels/{id}
• Update event

Some of these APIs are in Beta version, therefore,

APIs under the /beta version in Microsoft Graph are subject to change. Use of these APIs in production applications is not supported.

Idea posted on Microsoft User Voice, Update Teams Message/Channel Posts with Graph API.