Yes you may, BUT when you do you MUST go back to your capped off gas port and carefully check it for gas leakage. Also you must relight all appliances with a standing pilot light and verify that all intermittent electronic start pilots can be restarted also. Opening any gas line with no gas pressure on the line will allow a bubble of air into the pipes as the lighter-than-air gas escapes, so restarting any buildings gas service can be a hair puller if not done carefully and safely.