@Yvon12 You need to call Sky to do this.
You can call on 150 from a Sky Talk Line or Sky Mobile.
If you haven't got a current Sky Mobile or Sky Talk this link should help:
(UK) https://www.sky.com/help/home Scroll down and click on ‘Need more help’ and it provides a 0333 number
(ROI) on the same link change the flag in the very bottom corner to the ROI flag to obtain an 0818 number.
Stay on the line and don’t hang up if prompted to. Apparently the quieter times to ring are just after 7am or about 9pm.
@Yvon12
Be aware if you have 'in contract' discounts you may not be able to remove them. Also make sure cancellation of a certain add-on doesn’t cancel another part of a discount.