Sorry for the delay in responding. As Stig suggested it is in the owners manual but the instructions suck. Owners manual available here
https://www.kymcousa.com/manuals/ . Page 15 in book, page 19 in PDF.
(3) Oil Service Reset
Keep pressing MODE and ADJ buttons for 2 seconds at the same time to reset oil service.
Basically the odometer display has 4 modes, total mileage on the bike (odometer), Trip Odometer A, Trip Odometer B, and the Oil Service Odometer. With the key on, pressing the ADJ button for 2 seconds will switch display modes but you have to release the button and press it again to switch modes again and each time. Once you get to the Oil Service Odometer pressing the MODE and ADJ at the same time for 2 seconds will reset the Oil Service Light and Odometer