Along with those^ two excellent comments, when you get ready to refill the system I’ve found it best park the car under a slight angle, nose up. Leave the top radiator hose off the radiator but on the engine and refill the engine from that top hose using a funnel.
Then, when you’re close to getting it topped off, quickly move that top hose onto the radiator.
You get a better fill that way and it is less likely for you to have air bubbles in the system.