Law / Preparations for Leaving Poland and ZUS/NFZ insurance [4]

I did nothing while being in Poland.
After I had left, I sent e-mail to NFZ and Urząd Wojewódzki.
NFZ asked for: a document from University confirming that I don't study there anymore, confirmation of all payments made to ZUS and request for termination of the contract (a form found on their website). Later, they sent me confirmation that agreement is terminated.

Urząd Wojewódzki asked me to notify them in order to revoke my residence permission and to return my residence card in person or by post. I asked them if there a possibility to return it to Polish embassy, but haven't got any clear answer. Since my card has already expired, I haven't done anything.

While in the airport, upon passport check before leaving I was asked to show my residence card (since I was in Poland much longer than 3 month).

So in the end, there was nothing that can't be done by e-mail or by post.