Easiest way to get rid of it is to run a Sanitary Wash 5 to 6 scoops of Oxiclean with no clothes. Ater the unit has completed filling add 2 more gallons of hot water either through the flap area or the door. This cleans out the washer and may need to be done twice if the 1st time didn't totally clean it.
In the future you can keep this from reoccuring by using the Sanitary wash at least once a week. I do our towels, sheets and our boys underware in the Sanitary cycle so that's 3 loads a week for our family. I always add a scoop of Oxiclean with the whites.

I have this washer, and after replacing the boot once I have found two things that have kept it mold free ever since (4 years now):

1) Similar to what jakvis said, run an XXtra Hot Wash at least once a week without clothes, and just use regular detergent and liquid *chlorine* bleach (LCB) in the bleach dispenser, with the Bleach option selected. The LCB really will disinfect the entire inside of the washer quite thoroughly.

2) Most importantly, leave the door WIDE OPEN (not propped open/ajar, but all the way) after you have finished your wash for the day until the inside of the washer and boot are both utterly bone-dry. This will take several hours! Mold loves the dark and damp places, and by drying out the inside and boot completely you eliminate the conditions that can cause mold growth.