I don't think there's any need to get rid of healthy feeder fish after a few days if they haven't been eaten. Leo usually leaves one or two in there for a few weeks, then regains interest and eats them

. Two guppies aren't going to add much to tank waste and they will eat whatever scraps the turtle leaves behind as spotsmama said, so just leave them and don't worry about feeding them.
Ferd- I don't think that Ick is contagious to turtles, but on the other hand, it's risky to feed diseased food to anything so I wouldn't take the chance, its not worth it if your turtle does get ill. Are the fish in the turtle tank now? If so, I'd remove them.