Pinned
You can use CrowdNinja to make the process of pinning and unpinning messages much easier.
CrowdNinja requires the 'Pin Messages' admin right for this feature.
Find a message in chat that you wish to pin
Reply to message with /pin
By default, the message will be pinned silently with no notification to users. To ensure a push notification is sent to all users:
Find the message in chat that you need to unpin
Reply to message with /unpin
If you do not reply to a specific message, this command will unpin the most recent pin instead.
Useful for when you need to remove all pinned messages. All messages will be unpinned whether you reply to another message or not.
Add all after /unpin in the group's chat
Be aware, this cannot be undone. If called in error, you must manually re-pin messages.