I updated my watch this morning and now I am unable to delete a custom saved workout on my watch. I think the delete button was removed with the latest update. Thanks.
You have two other options. Since you are asking on the forum of Garmin Connect Web, try deleting it there, and then syncing the watch. It should disappear from the watch too. If it does not help, connect the device to a computer, with the USB cable, and delete the workout from the folder //GARMIN/Workouts/