Macbeth bears total responsibility for the murder of Duncan.
Yes, Macbeth, with malice aforethought, did with a dagger, kill King Duncan while he slept.
There is no question that Macbeth had been influenced by the three witches and his wife, Lady Mcbeth, to do the deed, but the final responsibility for the murder falls squarely on Macbeth.
It has been claimed that Macbeth merely carries out the wishes and desires of his wife. She does, indeed, do her very best to persuade Macbeth to finally do the killing, but Macbeth thought about it much earlier (Act 1, scene 3):
This supernatural soliciting cannot be ill, cannot be good. If ill, why hath it given me earnest of success, commencing in a truth? I am Thane of Cawdor. If good, why do I yield to that suggestion whose horrid image doth unfix my hair and make my seated heart knock at my ribs, against the use of nature? Present fears are less than horrible imaginings: My thought, whose murder yet is but fantastical, shakes so my single state of man that function is smother'd in surmise, and nothing is but what is not.
This shows, early on, that Macbeth is contemplating the "horrid image" of the murder of King Duncan. No one else can take the final blame.