How do I enable or disable the Twitter Retweet and Facebook Like buttons?
You can choose whether or not to display the Twitter and Retweet Facebook Like buttons.
Click Customize in the Settings dropdown for your space.

Choose whether or not you’d like the Twitter Retweet button and Facebook Like button displayed under your posts:

If you would like to remove the Facebook Like button but keep the Twitter Retweet button (or vice versa), you can customize your theme. Learn more about custom themes in Posterous.