Agree with JimB: check out correctly with the Port Police. You don't have to hand in your 'transit log' or DEKRA (or whatever it is called nowadays). You keep it and you can use it again if you return to Greece.

Furthermore, you do not have to leave 'immy'. You officially have 24 hours to leave after having checked out, but if you stretch that hanging at anchor in a nice bay; who would be checking that out? Take your time and select the correct window to leave regardless of officialdom.