I went from owning an espresso machine which I used religiously to drinking no coffee at all and no caffeine. I did not have any problems with headaches even though I depended so heavily on caffeine. But as the previous poster noted, biochemistries vary from person to person.
So you may need to taper down, using decaf if you get headaches. Drink lots of water also to flush your system out and help you get rid of the toxins.
You might also want to add an adaptogen like eleuthero (siberian ginseng) which can not only give you energy but help support your adrenal system which will be going bonkers. It's nonaddictive and safe.
Let me underscore - however - how good I feel without caffeine in my life. Even on days when I get only a few hours of sleep, I've learned to use water, exercise, and fresh foods to stay alert and focused. It's so worth it to get out of this destructive false energy roller coaster.