Just let the CO2 flow for a little while, and you should see it decrease.
I would just let your regulator off gas first (with the CO2 main cylinder closed). This will reset everything back to zero (make sure that the regulator knob is still dialed in (clockwise) so that any gas remaining in the regulator can be released. Of course, you could just unscrew the regulator from the CO2 cylinder as well...)
Thanks for the reply Darkblade48. Im a little confused here on your suggestion to let it off gas by closing the main cylinder(the regulator knob counter-clockwise), but also keep the regulator knob dialed in(clockwise) for the remaining gas will be released?
I must be interpreting this wrong