Yes it's a shared option with both iTunes and LW.
For iTunes, go to edit menu, Preferences -> Sharing & you will see two options.
Look for shared Libraries is what will affect this from LW.
For LW, go to LW's menu bar, Tools > Options > iTunes > Sharing & you will see options there.

The share option is designed for sharing playlists on a LAN. You can disable it from your particular account / computer by turning off Look for shared libraries in iTunes.