Yes, you can delete a Slack conversation. To do so, follow these steps:
Log into Slack.
Click the three lines in the top left corner of the main screen (left of the chat box).
Select “Deleting conversation.”
Type the name of the conversation you want to delete and hit “delete.
To delete Slack messages after time, you can use the following steps:
Click on the three lines in the top left corner of the screen (the “slack-bot” icon).
Select “Delete message.
No, deleting messages on Slack does not delete for everyone. Only the person who deletes the message is removed from the Slack team.
There is not a one-size-fits-all answer to this question, as the best way to bulk delete Slack files will vary depending on the Slack server and its configuration. However, some tips for bulk deleting Slack files include using a deletion tool such as SlackDeleter or SlackCleaner and creating a custom deletion policy for your team.
Slack offers an “offline read” feature that allows you to mark all messages as read on your account. To use this feature, simply click on the “read all” checkbox next to each message in your Slack history and then click the “mark as read” button.