In Zurich the only place to exchange old CHF notes is the Swiss National Bank, takes about 25 minutes to get there from the airport via train and then tram 2.

You can just walk in, no security screening, there are never more than 1 or 2 people waiting, and for 1000 francs they will just exchange them over the counter, no questions asked and no ID needed.

Only notes of the 6th series and 8th series can be redeemed, however the Swiss national bank will also take current coins and notes and change them to whatever you ask for. Silver-coloured 5 rappen are also accepted for redemption.

In theory, old notes can also be exchanged at the headquarters of the Cantonal Bank of each canton (not Zurich as the national bank is there), at the special National Bank agency counter, not the regular counters. This may require making an appointment or they have very limited opening hours. Some cantonal banks may refuse if you are not a customer, apparently this is not permitted but as a non-Swiss you can't do much about it.

Commercial banks in Zurich will not take old notes. But they may do if you have an account and are a high value customer.