Loke, the popular answer is no, you don't have to follow the ODP. However, I'm not sure how how the FAR quote below, which also applies to Class C and B airspace, supports that. Clearly, an ODP is established by the FAA. Anyone?
91.129 Operations in Class D airspace
(g) Departures. No person may operate an aircraft departing from an airport except in compliance with the following:
(1) Each pilot must comply with any departure procedures established for that airport by the FAA.
http://ecfr.gpoaccess.gov/cgi/t/text....1.3.10.2.4.15
Hawk