How do I stop orca from starting up on login?

Run this in a terminal:

gksudo gedit /etc/xdg/autostart/orca-autostart.desktop

change NoDisplay=true to

NoDisplay=false

Save, then open up Startup Applications and disable the entry for Orca.

For Ubuntu 13.10, open "Universal Access" and turn off screen reader

The "Seeing" tab is the default and includes this option