withdrawal - the act of withdrawing

abscondment, decampment - the act of running away secretly (as to avoid arrest)

absence without leave, unauthorized absence - unauthorized military absence

deviationism - ideological defection from the party line (especially from orthodox communism)

rejection - the act of rejecting something; "his proposals were met with rejection"

exposure - abandoning without shelter or protection (as by leaving as infant out in the open)

apostasy, tergiversation - the act of abandoning a party or cause

bolt - a sudden abandonment (as from a political party)