If your only aim is to leave the property you could do this

Write to your landlord a letter something along these lines:

Dear

I have just found out that I do not have a legal right to stay in Switzerland so i am going to leave, I wish you had told me that i needed a residence permit to take up a tenancy on your property before I moved in.

If you had maintained the property and it's contents to warrant my loyalty then I would have given you further notice, seeing as you haven't and I am residing in Switzerland illegally then I have already left.

Please find the keys enclosed

Fathers name

No forwarding address supplied

PS

If you want your deposit back don't pay rent until it is used up