If a character race/ template has an ECL modifier, this modifier can be erased over time. Without this adjustment, the race/ template would eventually become a serious hindrance on the character’s advancement.

Players may “buy off” their characters’ ECL adjustment one level at a time, once every three levels. This option becomes available once the character has acquired 3 hit dice for each ECL adjustment level (3HD for a +1 ECL, 6HD for a +2 ECL, etc.). The XP cost is 1000 * (current ECL -1).

See your friendly GM for details.