Payment method, how to change?

I have had account in Switzerland which thas not exists anymore, I would like to change it,

1.

It depends on what you did with your 'Apple ID'. If you have deleted it, it is no longer valid, it simply no longer exists and it no longer works. Then you cannot change it.

To understand about a deleted Apple ID, see the Apple articles below:

How to delete your Apple ID account

How to delete your Apple ID account – Apple Support (UK)

Understand and control the personal information that you store with Apple

Understand and control the personal information that you store with Apple - Apple Support

2.

If you stil have / know that Apple ID, check your Apple ID via your email box, see this Apple article: If you forgot your Apple ID

If you forgot your Apple ID email address or phone number - Apple Support                  

OR see -> Having trouble signing in?

https://iforgot.apple.com/password/verify/appleid

Try this -> If you can't connect or sign in to iCloud

If you can't connect or sign in to iCloud - Apple Support

See also -> Contact Apple for help with Apple ID account security

Contact Apple for help with Apple ID account security - Apple Support

If you find it and have fix it, see this Apple article: Change your Apple ID

Change your Apple ID - Apple Support (SG)

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

3.

If you then want to change Country or Region, you must comply with all regulations described here -> Change your Apple ID country or region -> Change your Apple ID country or region - Apple Support (KW)

IF you still need help, get more help and assistant from Apple directly, see Contact Apple for support and service -> Contact Apple for support and service – Apple Support (UK)