Use no-doz pills to quit without side effects: reduce/taper/titrate the dose down from one pill per morning to, part-pills, to none over a few weeks.
I quit every few years, and just stopping is very unpleasant. Using caffeine-only No-doz pills as above is cheap and easy. I’ve also done it by using instant coffee and reducing the size of the spoonful of coffee, although it’s mentally harder to break the habit that way. Edit: I guess heavy coffee drinkers might need to start at two pills (check dosage info on package: I've always been fine starting at one). They taste nasty bitter, but OK if quickly washed down with water.