Unlike sending emails, you can actually correct mistakes in Slack messages after you send them. Whether it is an embarrassing typo or you forgot to include a link, fixing the error is easy.
1. Hover your cursor over the message
2. When you see icons appear on the top right of the message click the one that looks like three dots
3. Select “Edit message” from the menu
4. Make the necessary changes to the message (you can even delete the entire message if you wish)
5. Click “Save Changes”
Note: This feature may not be available for your Slack team if your administrator has disabled message editing.