Close Photoshop
1) Put in /Applications/Adobe Photoshop CS6/Presets folder
Open Photoshop
2) Open a file with some layer styles with the eyeballs turned off
3) File > Scripts > RemoveUnusedLayerStyles

Note: This works on every layer in your file, it works on hidden layers, turns them on, then removes the hidden layer styles, then hides it again. You don't need to select anything in your file, just run the script.

Source: http://feedback.photoshop.com/photoshop_family/topics/photoshop_feature_request_remove_unused_layer_styles