What`s upp app - how to uninstall ALL data

I don`t need the What`s up app anymore. Now I tried to uninstall it (iPhone 4 and Mac Book Pro) BUT my contact details are still visible to other What`s up user!! I don`t want this because I already deletet the app, but other users are not informed about that. So they are sending me messages which I am not replying and they didn`t get a notification about it. That fact could provoke some trouble with friends...

Please, can you quickly advice how to get my name from the contact list / completely delete this app??