Undo: The recipient no longer wants to be contacted

In the recipients manu, I see this particular recipient, in the Deliveries tab has: "The recipient no longer wants to be contacted" for all the email deliveries.

However, in the "Non deliverables and address" section, I cannot find this user by email. 

How can I "clean" this recipient so it again can recieve emails? Client has requested to recieve emails back.