If it is like all the ones I've ever seen, the Peltier is glued to the heat sink, so you do not need to worry about that interface.

For the rest, yes, just unplug the peltier from its power supply, then unclip the peltier/heat sink assembly from the logic board. Be gentle; uneven forces here could, conceivably crack the CPU, then clean the old heat sink grease (probably powder at this point) with alcohol, apply a dab of new grease and carefully clip the peltier/heat sink back on.

The caution about not removing it really should be a caution about operating the board without it attached.

And if you need another one, for some reason...

http://www.shrevesystems.com/misc.html