After the coals from the charcoal or other fuel source such as wood has cooled off completely then you can place the cooled off completely coals from charcoal or other fuel source into a trash bag or trash can and dispose of them that way.
Just make sure the coals are not hot and run some water over the coals to be sure they're extinguished fully.
I have a partial dirt road in front of my house so I just dump the cooled off coals in the dirt area of the road.