Cancelar la suscripción de prueba gratuita de Adobe Express

if you subscribed via a mobile app store, cancel via that store.

otherwise, 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, check your account (https://account.adobe.com) for a payment problem. all payment problems must be resolved before cancellation is enabled, https://helpx.adobe.com/manage-account/kb/fix-failed-missed-payment.html

I want to cancel my free trial subscription on Adobe Express, before I'm charged.

I report that I have an active Acrobat Premium account.

By @CarlosCorrea

Adobe Acrobat Reader Premium and Adobe Express are separate applications. It's not clear which you have.

• To cancel Adobe Express for mobile 
  https://helpx.adobe.com/express/web/adobe-express-subscription/cancel-ios.html

• To cancel Adobe Acrobat Premium for iOS: 
  https://www.adobe.com/devnet-docs/acrobat/ios/en/managingsubscriptions.html#cancel-a-subscription

Jane