How do I delete a comment?
You can delete a comment that you posted on another singer’s recording. You can also delete any comments that other singers have posted on your recordings.
Inside the app: To delete a comment, go to the comment in question and swipe it left (tap and hold if you're using Android). Then, tap on the trashcan to delete the comment.
On Smule.com: Sign in to your account at Smule.com and move your cursor over the comment. Click on the X icon that appears to delete the comment.