A Nissan Murano's wiper arm is not difficult to remove. It will take only a few minutes with a socket wrench. During the ownership of your Murano, you will likely only have to do this one or two times, if at all, because the arms themselves do not wear out as quickly as wiper blades. However, if the arm is bent and damaged in any way, it will cause the wiper system to malfunction.
Remove the wiper blade from the arm. At the center of the blade, find the release tab. The blade should slide right off. This is necessary if you plan on reusing the blade later.
Remove the cover at the base of the wiper arm. This exposes a nut.
Remove the nut with a socket wrench. Use a glass-safe lubricant if the nut is old or looks corroded.
Pull the wiper arm off, but be gentle, so you do not damage any part of the wiper system.
Place a shop towel or rag under the exposed hook at the end of the arm. This is keeps the metal hook at the end of the arm from damaging the windshield, as you rock it back and forth and carefully cajole the arm off.