Remove the ash when the fire chamber is relatively cool. Use the Pyro curved shovel to slowly empty the fire chamber. Ash almost always contains some hot ember.
Never use a vacuum cleaner. Obtain a metal (non-combustible) ash container with a lid. Store outside on concrete or bare ground.
Pot ash can be great for your garden if your soils are acidic, use only ash from a cooled fire which used good quality wood.