Peel up the orange tape covering the right thermal sensor.

Use a spudger or your fingernail to pry the right thermal sensor off the lower case.

If you have a MacBook Pro 17" Model A1229 or A1261, repeat this process with the left thermal sensor. Note the locations are different, the right one is next to the inside fan screw receptacle. The left is on a line with the inside screw receptacle but 20 mm forward of it.