There is a termination term of one month.

If you're still in the required period of 1 or 2 years you wil have to pay the remaining months in one.

There are 2 ways of termination. For both phone contact is required. Why is that not possible?

One. Bij calling customer service via 0800-0402 (no charge). This is the fastest and most direct. After that moment the one month termination time goes.

Two: with this form (Dutch only): http://kpn.com/opzeggen . This takes longer then the termination period of one month. You will be called back to confirm it's really you to prefent fraud. (Dutch phone number required). However, if you did not answer the 6th attempt you're connection will be terminated anyhow.

The problem is that people on the line don’t speak English and “send” me to English-speaking colleagues. I’d rather fill in the form in Dutch. but none of the forms you provided with the link works for me; I can use Google, so I asked here if there are some forms online (I kind of had the same thing with TV from KPN, and a worker at the store gave me an online link that is not on google).
I don’t need internet from KPN at my new address, I do not leave the country and no one died
The contract is more than 3 years, I just want to cancel that and straight forward as it can be done.

The people on the phone are supposed to master English. You better then call a second time.

Further are above the possibilities.

You could't try it in a fysical KPN shop. Find a shop.

Via this community it is not possible for the KPN moderators to end subscriptions.

Hello @LisaKey, The fastest and best way to cancel your contract is, to call our free of charge number 0800-0402. the customer service department is supposed to speak english. I am really sorry that your first try didn't work out. 
For moderators it is not possible to cancel contracts.