From Official Wiki of the Renaissance Kingdoms

Eradication is the worst thing that can happen to your character: it is the outright deletion of your game account from Renaissance Kingdoms.

There are two causes:

It is possible to recover an eradicated account if the eradication was carried out by the administrators of the game (for example in the case of multi-accounting, only you will have to prove to them that they were wrong to delete your account ...)