Usually gas appliances are connected via a rubber hose called a 'Bayonet Cooker Hose' and to release these you press down on the coupling, turn anticlockwise a little, and the coupling splits, sealing the gas off in one go. However if you are doubtful about this, call an installer or at least turn the gas off at the meter before you have a go.
John
April 2009
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix gas cookers.