Disable "Tags" prompt in OS 10.9 Save dialog
When parsing all .plist files in ~/Library/preferences. I don't find any options that would match your request. 

If you want to try it yourself, here are the commands I used : 

Convert all plist to xml text files (because some of them (are|can be) binary files)  :
find . -name "*.plist" -exec plutil -convert xml1 "{}" \;

search the files for tag: 
grep -rie "&lt;key&gt;.*tag.*&lt;/key&gt;" .