Most of the rum that goes into the batter anyways gets cooked off while baking. So the cake is almost alcohol-free with just the rum flavor.  However, the glaze has a lot of uncooked rum in it. So there are two options to make it alcohol-free, 1. Don't pour the glaze over the cake and serve the cake without the glaze. The crumbs will be slightly dry in this case. 2. Make the glaze with rum extract and skip adding the rum.