You can remove annoying or unwanted sounds as well as change them.
Just go to the relevant folder and rename the file.
For example. The following 2 sounds are from the UI. I just put "X" in-front of the filename. If I want to use it agaain then I just remove the "X".
WL_NSDSheath.wav renamed to XWL_NSDSheath.wav
WL_NSDShot.wav renamed to XWL_NSDShot.wav
File locations:
Steam
C:\Program Files (x86)\Steam\steamapps\common\Scourge of War Waterloo\Base\Sounds
Matrix
C:\Program Files (x86)\Matrix Games\Scourge of War Waterloo\Base\Sounds