Edit: This question has a similar premise and there's a good answer with possible solutions there.
You can use the OpenURL action from the Nanoflow Commons module, the provided URL will be opened in the same tab
Hi,
Using Jquery code in javascript snippet we can open the URL link in same window,
Jquery code:
.buttonName.click(function() {
window.open("https://www.google.com","_self")
}