The Toyota Celica's rear wiper can be removed in a minute or less. You might want to do this for either of two reasons. If the wiper blade is old and worn down, you will need to replace it. You'll know it is time to replace the blade if it appears worn down on visual inspection or you hear it scrape against the rear window. Likewise, if the Celica's rear wiper arm becomes bent or otherwise damaged, it will need to be replaced.
Grasp the Celica's rear wiper arm just above the hinge and lift it away from the window. Be careful when doing this; unlike the front wiper arms, the rear wiper will not pull out to a completely vertical position and forcing it will cause damage.
Locate and undo the security locking mechanism. On most wiper frames, this simply involves pushing in a tab. Some frames may use a small lever instead of a tab. In either case, you'll find the release at wiper's middle connection point.
Pull the entire wiper frame assembly off of the wiper arm.
Another option is simply to remove the rubber wiper insert from rear frame. The frame will have a metal tab or another type of securing catch that can be gently pried open with pliers. The insert will easily slide out.
Place a sponge against the rear window and rest the bare wiper arm against the sponge. You should do this whenever you work on the rear wiper assembly, especially if the Celica will be sitting for a period of time. The metal tip of the rear wiper arm can damage the window glass.