[Jack Houpe]

Go and buy a 1/4" npt female cap then put a 1/4" compression to 1/4" male npt and screw the cap on then disconnect the air going into the valve and cap it off, that will stop your leak. You can get it at lowes ace or home depot. These are just for reference but not a bad idea to keep some on hand. 

https://www.amazon.com/External-Hexagon-...159&sr=8-1

https://www.amazon.com/ZKZX-Compression-...r=8-3&th=1