Work in Germany without registration

I have a couple of questions regarding the registration process in Germany and the Insurance.

I have been working in Germany for the last 10 years, I would like to come back to Spain and work remotely from there.

Can I do the de-registration (Abmeldung) and still work for my company?
Can I do the de-registration and give it later to the insurance company (Krankenkasse), whenever I found a job in Spain or a way to work permanently in Spain for my current company (Freelancer for example).
What would happen if I do the de-registration in the Krankenkasse?
How long can I work in Spain without paying taxes in Spain?

As extra info: I already lived in Germany for more than 183 days this year, so I have to pay the taxes in Germany as far as I know.
My company doesn’t have an office in Spain.