Realms Plus is a subscription for content and Realms personal server to be used with supported versions of Minecraft (game sold separately) on PlayStation® and other supported platforms on which you own the game (Minecraft Java Edition not supported); an active subscription is required to use Realms Plus content. Content varies over time and may not be available in all countries. After the free trial period, subscription continues to be charged at the then-current regular price (subject to change) plus applicable taxes unless cancelled. 
HOW TO CANCEL:
From a PlayStation®4 console:
Sign in to PSN™, then go to [Settings] > [Account Management] > [Account Information] > [PlayStation® Subscriptions]. After selecting the subscription you want to cancel, select [Turn Off Auto-Renew].
From a PlayStation®5 console:
Sign in to PSN™, then go to [Settings] > [Users and Accounts]. Select [Account] > [Payment and Subscriptions] > [Subscriptions]. After selecting the subscription you want to cancel, select [Cancel Subscription].