Realms is a subscription for a personal multiplayer 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). To cancel, see “How to Cancel” below. 
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].