Many levels of understanding for killing Buddha...
The most superficial one, don't be attached to the Buddha.
The second one, don't create, make a Buddha separate form this life and these sentient beings.
The third one, forget about the Buddha.
The fourth one, as you become one with the Buddha, the Buddha is killed on the spot, instantly. No traces of Buddha left.
and of course, these four understandings can be experienced all together, at once.