Done.
They did not issue a "release" letter, they just let me go. I guess they analyzed my situation, and the fact that I was not moving to anther state to "look for something", but I had a written proposal (offer of employment, in my case).
They wrote me "...we encourage you to stay and work in WA..." ("encourage" doesn't look compulsory at all), ..... "...If you move to another State, please continue to keep your contact details and email address up-to-date..... "