WhatsApp showing "last online" on certain contacts, but no WhatsApp icon on Address Book app I think my ex has deleted his WhatsApp account. I can still see his last online time in WhatsApp, but the WhatsApp icon does not appear next to his name in my Android address book.

Does this mean he has removed his WhatsApp and cancelled his account?
Possible reasons:  


He might have deleted his account permanently (probably changed his number).
He might have blocked you in his account.


There is no need to remove Whatsapp to do above tasks.