How to Remove or Swap the Ender Chest on a Horse
Taking the Chest Off
To remove an Ender Chest from a horse, interact with the horse while sneaking, or use the same interaction you would use to take a normal chest off a chested horse. The chest pops off and returns to your inventory (or drops at the horse's feet if your inventory is full). Make sure you have space before removing it so you do not lose track of it.
Swapping to a Different Chest
If you want to replace the Ender Chest with a regular chest, or vice versa, remove the current one first. A horse only has a single chest slot, so the game will not let you stack a second chest on top. Remove, then equip the new chest the same way you equipped the first.
Moving the Chest to Another Horse
Removing the chest does not delete your ender storage contents — the items live in your player's ender inventory, not inside the physical chest item. So you can freely move the chest from one horse to another, or store it in a normal chest, without any risk to your stored items. Simply remove it from the first horse and equip it on the second.