Step 1) Download Nartac for IIS
Step 2) Run and select Best Practices (Disables SSLv2/SSLv3)
That’s it, if you want the long and hard way, follow this technet article.
What does this tool do? It makes registry changes to your schannel which applies to all TLS channels, either HTTPS, SMTPS, or STARTTLS (others if you have them)