Something close I have considered, but is not correct, is "Bite the hand that feeds you". The reason this is not correct is because this simply means someone (actively) treats their helper poorly, whereas the situation I want to cover is the person completely ignores or snubs them.
I am looking for an idiom if possible that means completely snubbing someone that once helped you, especially someone the perpetrator depended on, or had a lot of frequent contact with before, but only because the perpetrator wanted to use the helper for their own benefit and advantage, then abandoning them / disowning them after they are no longer of any help to the perpetrator.
Not looking for an idiom or word that describes the person (which would be an adjective), rather, I'd like a word or phrase that is a verb.
Thanks