Remember, the left pedal spindle is reverse threaded. Turn it clockwise to remove the pedal when facing the crank arm. The right side is normal, so turn it anti-clockwise to loosen it.

Why is left pedal reverse threaded?

Relative to the crank arm, this radial force rotates CCW, which - via the process of mechanical precession - creates a CW torque on the pedal spindle (thus tightening it). The rotations on the left side are all reversed, so it must use the opposite threading to prevent the pedal from coming loose.

Are right pedals reverse threaded?

It is important to remember that pedal threads are different from left side and right side. The right side pedal has a right-hand thread (removes counterclockwise, installs clockwise). The left side pedal has a left-hand thread (removes clockwise, installs counterclockwise).