Help | How to delete scheduled messages?
The Slack scheduler app allows you to delete messages using the command /schedule delete.
You have three options for deleting messages:
Delete all of your scheduled messages by using:
/schedule delete all
Delete your last scheduled message by using
/schedule delete last
Delete a specific message by using the below command where messageID is your message ID
/schedule delete messageID
You can see your scheduled messages and retrieve message ID’s using the command /schedule list