Thank you kindly for taking the time to reach out to us today. I hope that the day finds you well! •ᴗ•
I want to thank you so much for your patience while I looked into your ticket today. Reading over your ticket I understand that you recently completed a character migration and would now like to look into reversing it.
I am afraid though that all free character migrations are final and irreversible. As this is a code limitation Customer Support cannot bypass this restriction.
There is currently no character service system in place for World of Warcraft Classic, so we don’t even have the ability to initiate a Character Transfer from our end in Classic. Classic is just not coded to support these kind of changes at this time.
If you’d like to see character services introduced to Classic, then I would highly recommend submitting a suggestion to let our developers know. https://us.battle.net/support/en/article/21518
If you have any other issues feel free to contact us again. Take care and have a good rest of your day.