This is a tutorial on how to block or unblock users in Google+. If you want to block a contact whose is part of your Google Circle then you do the following to block the person. Navigate and select the contact inside your circle and click the
drop down arrow available below the More actions and select Block from the available menu list.
The following dialog would appear displaying what happens if you block the contact. Click the Block <Contact Name> button to confirm your action.
To unblock the contact in Google+, click the Circles icon in your Google+ and navigate to the Circle