Alternatively, you can contact onstar by phone by calling : 1-888-4-onstar (1-888-466-7827). After contacting onstar, the adviser you speak with should be able to guide you through the process of canceling your service.
[header] How to deactivate onstar [title] Contact onstar. [step] If you want to cancel your onstar service immediately, you will need to contact the company and speak with an adviser. [substeps] The simplest way to speak with an adviser is to press the blue button on the onstar system installed in your vehicle.