Hi, I need a police clearance as I am leaving the country and my new employer requires this. Also, I need an affidavit for one of my certificates. I don't know where to look or start this process. Can anyone help, please?

It is very likely, that what you refer as a police clearance is what is called Strafregisterauszug or a criminal record certificate:

https://www.ch.ch/en/criminal-record-certificate/
Here is how you can get one:
https://www.bj.admin.ch/bj/en/home/p...fregister.html

In regards of the affidavit more information is needed. A basic certified copy can by obtained with any public notary, which are plenty around, just google it. If you need an affidavit issued by any specific organization (e.g. the one, who issued that certificate), then it would be logical to ask this organization for assistance.