Is he not called “emeritus” which means retired?
For this reason, and well aware of the seriousness of this act, with full freedom I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005, in such a way, that as from 28 February 2013, at 20:00 hours, the See of Rome, the See of Saint Peter, will be vacant and a Conclave to elect the new Supreme Pontiff will have to be convoked by those whose competence it is.
If he renounced his office of Bishop of Rome, Sucessor of St Peter, he is now only His Emminence Joseph Cardinal emeritus Ratzinger.
re·nounce rəˈnouns/
verb
verb: renounce; 3rd person present: renounces; past tense: renounced; past participle: renounced; gerund or present participle: renouncing
formally declare one's abandonment of (a claim, right, or possession).
synonyms: reject, refuse to abide by, repudiate "Hungary renounced the agreement"
So if he truly did renounced his office why does he dress and is addressed as a pope?