Does this 去 mean reduce?
去 in this context means " to remove". 

去 never directly mean "to reduce". You thought it does, because logically thinking, you know 'if you keep reducing something, it will eventually be all gone (removed).' 

Therefore you can say: "keep reducing until all gone" is one of the methods to remove(去). But 去 itself doesn't mean "to reduce"

If you hang(吊) someone by the neck, you are  killing him. but 吊 (hang) itself doesn't mean " to kill".