Good question... they max you can have will drop, however it will not delete anything that is already there, at least for now. For example if you have 3/5 it would change to 3/2, if you ever remove that one DB you can't get it back. I would not suggest for people to do this and for anyone to consider bringing their account below the limit as a future cPanel update could forcefully bring your account under the limit. We will not be responsible for loss of data in this case.