neutralize

To neutralize is to cancel the effect of something. Neutralize the acid, neutralize the threat, neutralize the advantage.

In chemistry it is exact: adding a base to an acid until the mixture is neither, at pH seven. In military and security language it is a euphemism for killing or disabling, which is one of the more evasive uses English has. In sport and argument it means cancelling out an opponent's strength. Note that neutralise is the British spelling of the same word.