Normally the ones painted red are to hold the two halves of the wheel together, the other ones are to hold the wheel to hub.
So undo the unpainted ones and remove the wheel from the hub , a large hammer may be usefull here. Then when the wheel is off remove the valve core to make sure all the air is removed from the tube then before you remove the other nuts try to press the beads of the tyre inwards . its difficult if you remove the nuts first.