Removing the airline from the push-to-connect fitting is a relatively simple process. How our fittings work, is once the airline has been pushed into the fitting, there are small teeth that hold the airline in place. When removing the airline from the fitting, the goal is to release these teeth allowing the airline to come out. You will notice on the fitting there is a collared end where the airline inserts into the fitting. This collared end is what releases the teeth holding the airline in place in the fitting. What you will need to do is first push the airline into the fitting, and while keeping pressure on the airline, pull back on the collared end of the fitting, opposite of the direction you are pushing on the airline. Once you have pulled the collared end of the fitting back towards itself, the teeth should release, and you should then be able to pull the airline out of the fitting.