by AverageJoe » Wed Jul 08, 2015 2:54 pm
As Aunstic said, all data related to game accounts is stored on the server. At the time you install and login to WoW, the data for the account you log into is downloaded and kept in the WTF folder on your local machine (World of Warcraft Classic\WTF\Account folder specifically).
If, for whatever reason, this folder is lost or deleted (Your HDD crashes, you accidentally delete it yourself, you uninstall WoW, etc.), it'll simply be recreated with the same data the next time you login. At most, you'll lose Options settings and addon configurations, which both can easily be reconfigured.