PWA: how to close an another window opened in pwa and get back to the main frame

When i open a new window (with window.open) i can’t close it. I try window.close, history.back nothing happened.

Notice that the same code, running in the browser (Firefox) works perfectly.

I am using firefox to render the PWA on android tablet. In my case the usage of firefox is mandatory.

I want to close the opened tabs and go back to my main pwa screen