Some are held on with a nut and others have a clip underneath that has to be pulled back to that the arm can be taken off.
Take it to autozone, they change it for free. If not you turn the wiper so its perpendicular to the wiper arm and push down.
Under wiper arm flap is a grub nut, Undo nut and use a Wiper arm removal tool (there not expensive approx £10) Remove Arm and Replace with New
get a wiper removal tool and it goes under the arm and you just pry the arm up off the splines to take it off.
This is pretty simple. Just turn on the wipers and stop them while the arm is in the middle of the windshield or there about. Then just change as any other wiper.
buy a small wiper arm puller to pull the arm off the taper once the nut has been rmoved
Flip up the cover on the end of the arm and undo the 12 mm nut. Pry the arm off the wiper motor shaft and simply press new one on. Be careful to align the arm a little past the wiper arm rest and tighten.
You can change the wiper blades by removing the retaining clip to the wiper blade arm. The wiper blade will come off and can be replaced.
Take a close look at where your wiper blades attach to the wiper arm to try to determine what type of attachment it is. Then see sources and related links below to view videos for the various wiper arm attachments.
To remove the wiper arms lift arm assembly and pry the release lever out with a screwdriver and lift the wiper arm off . To change the wiper blade pull the wiper blade/arm assembly away from the glass , insert a small screwdriver into the slot and pry up or depress the tab (depending on model ) to detach the blade assembly , Slide it off the wipper arm and retainig stud , you
# Raise the rear wiper arm finish cap to expose the wiper arm nut. # Remove the rear wiper arm nut (1). # Lift the rear wiper arm assembly (2) away from the rear window and remove the wiper arm from the pivot shaft. The cap tilts up toward the arm
To replace the blade, it just unclips and the new blade clips on. To replace the wiper arm, the black cap at the base of the arm pops up and the arm can be unbolted.
Remove the wiper arm from the wiper motor. Remove the wiring harness from the wiper motor. Remove the wiper motor retaining bolts. Reverse the process to install the new wiper motor.