Like everything else, the manufacturers are looking to
save money by not putting in certain items that they
deem as not necessary, which in this case is a drain plug. The one plug you see is called a 'sight plug', and with the machine on a level surface, add the recommended 'oil', (not grease),until it starts to come out of the hole. The only options I see for draining the existing oil is to disassemble the unit or drill and tap your own drain plug. Unless you want to tip the whole machine so the sight plug is on the bottom, and draining it that way.