Can I disable Toolbar in specific theme? I have two active theme, and switching between them by themekey on specific paths.

theme #one is my main theme, and some contents load in theme #two in a modal box (lightbox2).
I need disable Toolbar on theme #two because it's load Toolbar too and I don't want it there.

my question is how can I disable Toolbar in theme #two?
You'll have to use hook_page_alter from within a module to unset $page['page_top']['toolbar'] — you can't do it from within a theme.

There is a module for that: Toolbar Visibility.