How to access a method in a Javascript Function at the angle?

Question

I am using a plugin in Jquery and it works very well in Angular, however I want to call a service method within a function of an alert, follows below the code:

click event that creates the modal

<button class="button small alert" (click)="didTouchDeleteBrand(brand)"><span class="mif-bin"></span> Excluir</button>

method that displays the modal and when clicking yes it generates the error

ERROR TypeError: Cannot read property 'brandService' of undefined

code:

  constructor(private router: Router, private brandService: BrandService) {}

  public didTouchDeleteBrand(brand: Brand) {

function removeItem(teste){
  this.brandService.deleteBrand(teste.BrandID).subscribe(
    () => { 
      this.loadTableContent('');
    },
    (err) => { console.log(err); 
    }
  );
}
Metro4.dialog.create({
  title: "Confirmação de exclusão",
  content: "<div>Deseja realmente excluir este item?</div>",
  actions: [
      {
          caption: "Sim",
          cls: "js-dialog-close alert",
          onclick: function(){
            console.log(brand.BrandID);
            removeItem(brand.BrandID);
          }
      },
      {
          caption: "Cancelar",
          cls: "js-dialog-close"
      }
  ]
});
}