code: func (p *PushCenter) UnregisterHandlerForIdentity(identity Identity) {
  
  	if identity.Name == AllIdentity.Name {
  		p.defaultHander = nil
  		return
  	}
  
  	if _, exists := p.handlers[identity.Name]; exists {
  		delete(p.handlers, identity.Name)
  	}
  }
docs: // UnregisterHandlerForIdentity unegisters the given EventHandler for the given Entity Identity.