first, remove your action cover, bolt and bolt carrier group from the rifle.
next, flip the lever, that is located on the right side of your rear sight block, upwards (clockwise about 90° or so).
this will enable you to lift and remove the upper hand guard/gas tube assembly.
clamp the rear 'flats' on the side of the gas tube in a vise or hold them in a pair of channel-lock pliers. using a rag for grip and padding, CAREFULLY rotate the upper handguard wood around the gas tube axis 180°.
to remove the lower handguard, flip the lever that is located at the right side/front into the 'up' position. this may require the use of a small screwdriver to do so.
once the lver is up, slide the front retainer plate forward and away from the lower handguard. once it is clear of the handguard, pull the front of the handguard wood down and forward.