Whenever an app requests access to your personal data, the system will pop up a dialog box, similar to the one below, that allows you to either accept or deny the request. As the window says, if you deny the request, you’ll take the first step to block access to your personal information. You should know that regardless of what option you choose in this dialog box, the program will be added to the “Privacy” system preferences. The only difference is that if you accept the request, then the program will be enabled in these preferences, while if you reject the request, the program will be disabled and unchecked in the preferences. If you made the mistake of unknowingly allowing a program to access your personal data, but now want to revert it, simply follow the steps outlined below:

  1. Open System Preferences from the Apple menu.

  2. Click on the “Security & Privacy” icon.

  3. Here, in the Privacy tab, you’ll see a list of services that you’ve configured, including Location Services, Contacts, etc. Selecting an individual item will show you the programs that have so far requested access to that particular service. You can simply check or uncheck the box next to the program name, which will then either grant or revoke access.

Note: You might have to authenticate using the “Lock” icon in order to make changes. This approach can be really convenient, but once a program is added to the database, there is no way within System Preferences to remove any programs from the privacy list. The only easy way to do this is to use Apple’s built-in “tccutil” command to clear the application entries for a specific privacy service. Using this, for instance, you can reset all the applications that you have allowed access to in your Facebook account and force them all to again request access. Then you can simply allow and deny various requests according to your needs. To do this, simply open up Terminal from Spotlight or “Applications -> Utilities”:

Run the following command:

Here, you’ll need to replace SERVICE with the name of the one you wish to reset, which can be “Twitter”, “Facebook” or even “AddressBook” for your contacts. The full list of supported services include:

AddressBook CoreLocationAgent Facebook Twitter Reminders Calendar SinaWeibo Accessibility

One last tip: if you wish to remove everything, then you can use the keyword “All” instead of removing each surface one by one.