If you have an excess amount of fat that has cooked out of your ground beef mixture while your sheet pan taco was baking, then you can very carefully tilt your pan and pour out the excess grease into a separate container. Once that grease has cooled, you can dispose of it. This will make sure that your sheet pan tacos are not sitting in any excess grease. Note, you really want to make sure you use a slotted spoon to drip off as much excess fat before placing the ground beef onto the flour tortillas. If you use leaner ground beef, then you will not have as much excess fat to worry about.