1.
To do away with something means to remove it completely or put an end to it.
The long-range goal must be to do away with nuclear weapons altogether.
PHRASAL VERB : V P P n
2.
If one person does away with another, the first murders the second. If you do away with yourself , you kill yourself. ( INFORMAL )
...a woman whose husband had made several attempts to do away with her.
PHRASAL VERB : V P P n , also V P P pron-refl