Site oficial diz:

When are characters automatically deleted?

Characters under level 20 are deleted automatically if they are not used within a period of n months where n is equal to their level. Please note that this rule only applies to characters on free accounts. Characters on Premium Accounts will not be deleted automatically at all.
When a character has been deleted, the name will still be blocked for some time in order to make sure newly created characters are not mistaken for the deleted character.
Ainda assim, acredito que esta regra não se aplica a qualquer situação, já que quando fui banido por um mês não tive os meus characters Level 1 deletados.