resign, vacate, renounce, give up - leave (a job, post, post, or position) voluntarily; "She vacated the position when she got pregnant"; "The chairman resigned when he was found to have misappropriated funds"

retire - go into retirement; stop performing one's work or withdraw from one's position; "He retired at age 68"

top out - give up one's career just as one becomes very successful; "The financial consultant topped out at age 40 because he was burned out"

pull up stakes, depart, leave - remove oneself from an association with or participation in; "She wants to leave"; "The teenager left home"; "She left her position with the Red Cross"; "He left the Senate after two terms"; "after 20 years with the same company, she pulled up stakes"

fall - lose office or power; "The government fell overnight"; "The Qing Dynasty fell with Sun Yat-sen"

minify, decrease, lessen - make smaller; "He decreased his staff"