unpin
Use this method to remove a message from the list of pinned messages in a chat. If the chat is not a private chat, the bot must be an administrator in the chat for this to work and must have the 'can_pin_messages' administrator right in a supergroup or 'can_edit_messages' administrator right in a channel. Returns True on success.
Parameters
business
Unique identifier of the business connection on behalf of which the message will be unpinned
chat
Unique identifier for the target chat or username of the target channel (in the format @channelusername)
message
Identifier of the message to unpin. Required if business_connection_id is specified. If not specified, the most recent pinned message (by sending date) will be unpinned.