How to hide own location from yourself?

Hello everyone
My mother can access my facebook account and I want to hide my own location in the "active sessions" so she can't see where I'm at or when I'm signing in. I know it's possible but I just don't know how to do it.. I have OSX 10.5.8 and i'm using both Safari and Opera.
Help me out please
Thanks

See original post by mcu_808