How to sell gold bars in the game

Nothing in the game can be sold and this is specifically stated in the Terms and Conditions you agreed to when you started to play. That gold is for this one game only in which you play. Its sole purpose is to have fun playing your game. If you have too much, then save it up for the next big event, then use it to buy boosters and extra moves. If you are living in one of the eligible countries you could play the music event using that gold.