Follow these steps:
  1. Open WowApp.
  2. Go to your Contacts list and right click on the contact you want to block.
  3. Then select Block Contact.
  4. You can now select if you want to also Unfriend that particular contact.
  5. Make the desired changes and click Block.
 Unblocking a Contact
  1. Open WowApp.
  2. Click on Contacts -> Blocked Contacts.
  3. Select the contact you want to unblock and click Remove -> Save.