Hey @JesseKoper, 
Thanks for your post. If you wish to delete a comment you have left on your own activity or another athlete's activity, ensure you are viewing the comment using the Strava mobile app and then swipe the comment to the left to reveal the Delete option.
 
Alternatively, if you view the comment using the Strava website, hovering your mouse over the comment will reveal a Delete option which can be used to remove the comment from the activity.