I haven't checked the wiring diagram, but a washer fluid warning is usually a simple two-wire contact switch activated by a float of some kind. If you can access those wires and either jumper them (<most likely) or leave them permanently open (whichever is required) the light will stay off.

Hint: if you do this, cut and jumper the wires where you can repair them if it turns out this doesn't work.

 

Removing the bumper fascia etc. assumes replacing the entire tank since that's what Nissan calls for in the service manual. That sensor plugs into the bottom of the tank and if you remove the wheel well you can see most of the tank so you might be able to get to the sensor without removing all that other stuff. You should try to check it out anyway in case the problem is not with the sensor, but with the wiring/connector.

 

Simple fix:
remove the passenger front wheel and pull the forward plastic mud shield from the wheel well, you will expose the entire washer container and washer pump and or the sensor....here is a couple videos to watch that might help, it's not about the Murano specifically but it gets my point across and makes a easy job of it, parts are available on amazon.com really cheap.

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