(This answer is to expand the comment from the user DG')
In a fresh install of ST3, the command
~$ find -iname "*latextools*" outputs:
As you can see, the file LaTexTools.sublime-settings is already there. BUT, this is not the one you should edit
The first lines of that files explains what to do:
DO NOT EDIT THIS FILE!!! Open the Command Palette and run the "Reconfigure and migrate settings" command. Alternatively, select the "Reconfigure LaTeXTools and migrate settings" item from the Preferences, Package Settings, LaTeXTools menu, or open the ST console and type
This is more or less what the user DG' sugested in his/her comment.
After following those instructions you will have the correct file to edit in: