1) Add one key in AppSettings in web.config file as
<add key="IsVisible" value="1" />
2) In page.cs where that button resides check key value as
bool IsVisible = ConfigurationManager.AppSettings["IsVisible"].ToString() ;
if(IsVisible = "1")
{
yourbutton.Visible = true;
}
else
{
yourbutton.Visible = false;
}
Hope this helps!!