As mentioned in this thread:
https://forums.coronalabs.com/topic/9540-delete-cookies-from-webview/
the webView:deleteCookies() call doesn’t work on OSX builds.
Does anyone - mayby Perry 
- know where the webView stores its cookies?
Is it somewhere in this folder ~/Library/Cookies/
I tried deleting the com.mycompany.myapp.binarycookies but it doesn’t seem to have any effect.
I am thinking if I can locate the cookies I can delete them manually by running a shell script in my app.
Thanks.