When navigating with clearHistory flag set to true with router-outlet, the history doesn't get cleared. So the flag has no effect at all.
Button text="login" [nsRouterLink]="['/main']" clearHistory="true"></Button>

The same applies when calling navigate through code:

navigateHome() {
    this.routerExtensions.navigate(['/home'], { clearHistory: true });
}

When I call the canGoBack() after navigating I always get true.
this.routerExtensions.canGoBack() => returns true;