Sadly I do not think this is possible - but please check with an accountant first -
w w w cohesaconsulting.es
if you are near Coin in Malaga?
We can highly recommend Maria.
NB My OH is receiving UK state pension, wanted to work here (small market garden - read very small top up income!)
But by the time all the ‘world wide income’ (i.e UK pension had been taken into the personal allowance), Eu275pcm autonomo SS was not viable… I don’t think you can opt out!
Check with a professional who knows Good luck!