I recently installed the Nitrux–UMD icon theme, and I'm wondering how to turn off the Unity gloss that's being applied over the unity bar icons.
This is how it looks—
This is how it should look—
I think you can try to edit the images in the /usr/share/unity/folder with your version number..
Here you have my result:
Before edit the image:
After edit the iamge:
Remember that you have a backup , So if anything goes wrong rename the backup "launcher_icon_shine_54.png.bak" to "launcher_icon_shine_54.png" logout and login to have the original unity.
I hope this would be useful.