Is it hard to remove stucco from the ceiling?

Not necessarily as hard as it is messy & time exhaustive...You might want to consider applying a drywall veneer over it. They make a drywall that is not as thick as your standard 1/2" and 5/8" thick sheets. There is also 1/4" & 3/8" thick as well. With some panel adhesive & drywall screws, making sure that you're screwing into the joists above the stucco, you apply some panel adhesive to the backside of these sheets & install them on the ceiling right over your existing stucco...You'll have to tape & mud the finished product & texture if desired....This, all-in-all, should save a whole lot of time as well as a huge mess...Best of luck...