You can revise/edit your submission as follows:  In the Mission tab, move over to your “Completed” column. Select the mission you would like to revise.  Press the 3 dots (…) to the right of your team’s name, and press “Edit Answer.”

You can delete your submission as follows: in the Mission tab, move to your “Completed” column. Select the mission you would like to delete.  Press the 3 dots (…) to the right of your team’s name. Press “delete submission” and confirm with “Ok.”