Managing your Twitter and Facebook Accounts in Mountain Lion
On Mountain Lion (Mac OS X 10.8), Twitter and Facebook are managed in System Preferences. In Pocket, when you share to Facebook or Twitter for the first time, it will ask for permission to access these accounts.
To add or edit your Twitter and Facebook accounts, go to Apple () > System Preferences > Internet Accounts > Mail, Contacts & Calendars.
To allow or disallow Pocket from accessing either of these accounts, go to Apple () > System Preferences > Privacy & Security. Then, go to the Privacy tab, and select either Twitter or Facebook to control access.