How to keep a door open without a door stop. This will also prevent the door from locking. When you push your door open you expect it to stay that way. However placing the coin on the door latch may not hold the door open. Put a slight bend in the old hinge pin.
If you put the door stop in the gap so the door couldnt close instead of under the door holding it in place you cat would be able to get in and out fine. The striker on the door handle will help to keep the door hinges aligned while you remove the pin. Place your hinge pin on a scrap piece of wood. If your door only has two hinge pins then completely close it and remove the hinge while the door is in this position.
This door hardware article discusses the different types of door stops that will positively hold doors in the open position. The reason your door wont stay open is probably that the door frame or the wall its attached to was installed slightly out of plumb. This can hold the door handle at an open angle allowing you to push the door open and closed without turning the knob. Hold open door stops.
Depending on the gap between your door and door frame it may just allow you to push the door open and closed. In an emergency it may become necessary to close a door and ensure it does not come open until the emergency passes. In most cases you can rely on a lock but sometimes a normal lock is not sufficient.