Hi Damir,
Welcome to Pier!
Is it possible to disable the "Add a
Note"-Component?
Sure. Login as admin and edit /system/templates/environment. This is
the page that describes the layout of your book. The note component is
embedded with '+/system/components/notes+', just remove that part if
you don't want it.
Lukas
--
Lukas Renggli
www.lukas-renggli.ch