We can only disable the "like" link on on Specific Posts.
Have you tried disabling this like button setting on your sharing page?
Settings > Sharing
WordPress.com Like Button
___Show a like button and who has liked my post on all of my blog posts above the comments section
I did and the "like" button in the Admin bar still displayed. :(
However you can report this like button spammer to Staff. They will reactivate the support link early Monday, October 10th (UTC). Here’s the link http://en.support.wordpress.com/contact/ After you use the searchbox, under the search results, at the bottom of the page there will be a section that says “Have you found the answer to your question?” You can choose either “Yes I found the answer to my question.” or “No I didn’t find the answer to my question and I would like to contact support for help.” The no option will reveal the contact form.