You can manage your subscription from your iOS setting.

First make sure you're logged in with the same Apple ID you made the purchase with. Then, do as follows,

On the Home screen, tap Settings.
Tap iTunes & App Store.
Tap your Apple ID at the top of the screen.
Tap View Apple ID. You might need to sign in.
Under Subscriptions, tap Manage.
Tap the subscription that you want to manage. In this case, Recolor.
Use the options to manage your subscription.

Here is Apple’s guide on how to manage/cancel your subscription: https://support.apple.com/en-us/HT202039