How do I cupple off the gas pipe on the cooker as I am having an electric cooker

"Cupple off" is not a common term. Do you mean cap off? Can you describe or photo the piping and fittings? Depending on the fitting, you have a couple of options. If it is a flare fitting, you can buy a flare cap. If it is a pipe fitting. Probably 1/2 or 3/4", you can install a pipe threaded cap. A little more info would help.