Sorry for the inconvenience. Unfortunately we do not offer de-evolving services due to technical restraints. -Shinohara
Unfortunately, I'm sorry to inform you that we offer these services exclusively to make up with failed evolutions as it would be irreversible and make the Pokémon useless; in your situation. (e.g delevel a pokemon from 100 to 99 as it could not evolve anymore).
I'm sorry to disappoint you but i hope you can understand. -Shinohara