A command line utility for OS X to remove Safari cookies for a specified domain.
removecoookie example.com
Note: RemoveCookie is pretty dumb. It deletes all cookies with a domain ending in whatever string you provide. So removecookie example.com deletes cookies for example.com and all subdomains of example.com (i.e. blog.example.com, beta.example.com and so on). This also means that removecookie com will delete *any cookie for all .com domains, so be careful (thankfully, not a lot of harm can come from deleting cookies — the worst you'll likely experience is losing the contents of a shopping cart or having to log in to a site again).
I've done virtually no testing. Version 1 has worked for me on most, if not all, versions of Safari from OS X 10.7.5 with Safari 6.0.2 through OS X 10.10. Version 1.01 is required on OS X 10.11 and later. It will likely work with 10.6 (and possibly earlier), but you may need to change the build settings in Xcode.
RemoveCookie is provided as-is with no warranty or guarantee of any kind. You're free to use or modify it however you like for non-commercial use. If you come up with any useful or interesting modifications, feel free to submit a pull request.