Yep, happens all the time as the pulley's get older.
Change it in the car. Pretty easy job. Sometimes they come right off, other times they are a pain and require a puller.
To crack the pulley bolt lose you can do one of two things without the use of an impact gun if its not available. Put the car in gear ebrake up hard and wheels chocked, keep at least the drivers side wheel on the ground and take a breaker bar and socket to it. or if you want to cheat and make it even easier. Just put the breaker bar on the pulley, again passenger side lifted up, car in neutral, make sure the bar is resting against the control arm, blip the starter and it will break the bolt loose in an instant. Pretty easy trick.
Just make sure when you put the new pulley on to torque the bolt down good using the first metho d i said again if an impact gun is not available.