Résiliation de mon abonemment

you can't cancel by letter.

make sure you're aware of the cancellation terms by selecting your plan type (at the top of the page here), https://helpx.adobe.com/manage-account/using/creative-cloud-subscription-terms.html



and for info on how to cancel your subscription, this page describes the few steps involved, https://helpx.adobe.com/manage-account/using/cancel-subscription.html

p.s. if you're contacted by anyone (via email or private message), it's much more likely to be a scammer than an adobe representative.



if you're unable to follow the steps described, you'll need to await help from an adobe employee for the next step.  (if you don't get a reply here from a badged employee within 24 hours, repost.)