stultify

Verb

• deprive of strength or efficiency; make useless or worthless
  • This measure crippled our efforts
    
  • Their behavior stultified the boss's hard work
    

• cause to appear foolish
  • He stultified himself by contradicting himself and being inconsistent
    

• prove to be of unsound mind or demonstrate someone's incompetence
  • nobody is legally allowed to stultify himself