If you cancel now then you will not have a cancellation marker against your name, which if you did, would make your quotes astronomical. If you reckon you're going to be cancelled on. Do it first.
After, look for a quote that isn't telematics to avoid this in the future. Do not take one out under your parents name for yourself as that's fronting which is illegal.
I would wait and see if they cancel your insurance, if they decide to cancel it you still have the option of cancelling it before the 7 days. they normally give you a 7 day notice. but i would go with the advice above
Or you could just not speed and not have to worry.