I used to have a 10 person realm I subscribed to through iOS. I wanted to downgrade so I created a new 2 Person realm.

I renamed my old 10 person realm "delete" and kept it around till it expired so I could still look at it if I wanted to.

It is now expired and there is no way to delete it, or even any way to rename it from "delete", so now I have a realm permanently stuck in my list of worlds that is useless and annoying.

This has been asked many times but never really answered:

https://feedback.minecraft.net/forums/358536-minecraft-realms/suggestions/17649811-can-t-delete-closed-or-old-realms

https://feedback.minecraft.net/forums/358536-minecraft-realms/suggestions/14814300-mojang-can-u-add-a-delete-butten-for-realms-if-u-m

https://feedback.minecraft.net/forums/358536-minecraft-realms/suggestions/15577149-how-do-you-delete-a-realm

https://feedback.minecraft.net/forums/358536-minecraft-realms/suggestions/13449177-i-want-to-can-delete-my-realms-server-and-create-a

https://feedback.minecraft.net/forums/358536-minecraft-realms/suggestions/13414023-how-to-remove-realms-server-in-my-server-list

http://www.minecraftforum.net/forums/minecraft-pocket-edition/mcpe-multiplayer/mcpe-realms/2700243-how-do-u-delete-trial-realms