How do I reverse a permanent health buff?

Since you can't use the developer console it might very well be unsolvable, but they might correct it in a new patch.

Few ideas I've got:

• Try to become a vampire, when you are standing in sunlight, all your attributes get permanently (until it is night or you are indoors) decreased, the magnitude depends on which stage you are.

• There is an effect, accessible only by using alchemy, that permanently lowers health. It is not the damage one, but Ravage should do it (if I understand it correctly). Although I don't really know whether the potions you create with both positive and negative effects are classified as potions or poisons.

Both of these effects are reversible and might very well not be of any good, but you can at least try.
I am sorry I couldn't provide anything better.