I\'ve got a modal:
If you are using https://ng-bootstrap.github.io/ (as indicated in your question) things are extremely simple - you can just open a modal and either close it from a template (as in your code) or programmatically (by calling close() method on the returned Object of type NgbModalRef).
Here is a minimal example showing this in action: http://plnkr.co/edit/r7watmQuyaUQ8onY17Z1?p=preview
You might be either confusing different libraries or maybe there is sth more to your question but it is hard to say more based just on the info provided.