Thank you for contacting us for support. It is possible - as in the theory that nothing is truly impossible but it’s not going to be something that is easy to do.
You can move the data under the user by setting up another user under the other account and running an rsync. OR if you don’t care much about the data - or have totally backed it all up, we CAN remove a user from your account completely and you can re-add it to the new one.
I’m afraid at this time that we do not offer a way to have this done automatically. If you have any other questions or need any support please be sure to let us know.