Definitions of neutralize:

• verb:   make politically neutral and thus inoffensive

  Example: "The treaty neutralized the small republic"

• verb:   make chemically neutral

  Example: "She neutralized the solution"

• verb:   make ineffective by counterbalancing the effect of

  Example: "Her optimism neutralizes his gloom"

• verb:   make incapable of military action
• verb:   get rid of (someone who may be a threat) by killing

  Example: "The double agent was neutralized"

• verb:   oppose and mitigate the effects of by contrary actions