neutralize

make politically neutral and thus inoffensive; "The treaty neutralized the small republic"

make ineffective by counterbalancing the effect of; "Her optimism neutralizes his gloom"; "This action will negate the effect of my efforts"

oppose and mitigate the effects of by contrary actions; "This will counteract the foolish actions of my colleagues"

get rid of (someone who may be a threat) by killing; "The mafia liquidated the informer"; "the double agent was neutralized"

make incapable of military action

make chemically neutral; "She neutralized the solution"