De- and Re-authorize PC / Mac from / on Adobe Digital Editions

Just had the worst custumer service experinece in my life.

All I needed to know from the Adobe Helpdeks was how to de- and re-authorize PC / Mac from / on Adobe Digital Editions, and all I got was a silly aryicle and the advice to post my question in the community ...

Which I do, hoping someone can help me ...

I purchased an English e-book, for which I need to run the acsm throug Digital Editions in order to transform it into e-pub. This usually works very well, but with the latest one, I get an error message stating I do not have access anymore and have to re-authorize the Mac for Adobe Digital Editions.

I did a totally new re-install, still the same.

I tried to de-authorize, can't do it ...

Thanks for helping out!