I highly recommend getting all the Swiss paperwork 100% in order, at all the relevant offices, before leaving Switzerland.

This includes de-registering, and also closing and paying anything else outstanding, such as tax if applicable in your case, ending contracts for internet and phones, subscriptions to anything, memberships, pension moneys, health insurance, other insurances, making arrangements with your landlord about when your remaining deposit/heating bill will be refunded or a top-up payment required from you (could be up to one year from now) etc.

You might also find some helpful advice in these two threads:
https://www.englishforum.ch/leaving-...itzerland.html
https://www.englishforum.ch/leaving-...e-left-nl.html

Any part of this that you do not do properly before you go will come back to bite you, one way or another, afterwards, and will end up being a great deal more work when attempted from abroad.