How to remove previous pages from memory?

I'm using an implementation of Master/Detail in my Forms app. The problem is that even after I change pages the previous one is still running, I even had to do some inactive/isActive code in order to stop the code execution of those pages.

This is how I change pages:

        public void GoTo(Page page)
        {
            Detail = new NavigationPage(page);
            IsPresented = false;
            UserDialogs.Instance.HideLoading();
        }

Then I do:

Application.Current.HomePage.GoTo(new ServiceSelectionPage());

But the previous page is kept running. What am I doing wrong? Or how do I remove those pages from memory? I tried setting Detail = null to no avail.

Thanks!