Click on the workout you want to delete. A description/title of the workout comes up with a little black check mark in a box next to it to the right of your screen. there is a light gray arrow under that. click on that and an option comes up to delete the workout.
You can also drag that workout to another day if say you decided to do it tomarrow.
Yes, it's VERY light. After seeing the tutorial, i thought something's wrong w/mine, I don't have an arrow! Then, I looked again very closely & lo and behold, there it was!