conf/char_athena.conf https://github.com/rathena/rathena/blob/master/conf/char_athena.conf
// Restrict character deletion by email address or birthdate.
// This restricts players from changing the langtype and deleting characters.
// Defaults based on client date.
// 1: Email address
// 2: Birthdate
// 3: Email address or Birthdate
// IMPORTANT!
// - This config only works for clients that send 0x0068 or 0x01fb for delete request.
// - Use langtype 1 for newer clients (2013+), to use 0x01fb.
// - Clients that are not using 0x0068 or 0x01fb, only use birthdate (YYMMDD) as default.
char_del_option: 2
if u want to use email, then change the option to 1