How to remove coolant from window air conditioner?

This is not a Do-It-Yourself job.

Because refrigerant is very dangerous to handle - you could suffocate yourself or someone else in the room - you need to have the right tools and test equipment and must have been trained so that you know what you are doing.

Any air conditioning unit that has developed a fault must be thoroughly checked by an expert to ensure that a) it is running safely and b) there are no leaks of refrigerant. Call a Licensed Heating, Ventilation and Air Conditioning (HVAC) Technician.