For Ubuntu 16.04 the steps are different:
Open a terminal
Become root
sudo su -
The lenses are now apparently controlled by scopes
cd /usr/share/unity/scopes
The next command will show the files that contain a shortcut definition
grep -R "Short" *
Make a copy of the existing files (just in case) and verify they copied.
mkdir ~/scopes
cp -rp * ~/scopes
ls -Rl ~/scopes
Remove all the Shortcut entries - if you would rather just disabled some of the shortcuts, then edit the specific files that returned from the previous command.
find ./ -type f -exec sed '/Shortcut/,+1 d' {} \;
Verify all the shortcuts are removed
grep -R "Short" *
This takes effect immediately. The shortcuts do not disappear from Keyboard Shortcuts menu, however.