Yes, it's very easy, just 3 screws holding the gearbox to the motor. However, you don't need to remove the gearbox to clean and oil it, the plastic cover just slips off and you have complete access to all the gears.
If you do decide to remove the box, watch out for the tiny spacers that will fall out when the screws are withdrawn, I do it over a box just in case.
Chas