Awkward or not, you have to tell them you’re not interested in dating them. Politely, of course. If they can’t handle that, it’s their problem, not yours. I’ll tell you right now, it’s not a good idea to stay friends with someone who has romantic feelings for you until they truly move on, because chances are they’re going to be waiting for you to change your mind. And any friendly gesture you make to them will be taken as you finally coming around. Tread lightly. Just be honest with them.