Hii dear, 

Yes, obc category candidate can participate in ojee counselling Candidates belonging to reserved categories can seek admission to B.Tech programmes through OJEE under their respective categories provided they meet the OJEE reservation criteria, since there is no reservation quota for OBC category candidate, therefore they are considered in general category only, and no reservation for them in state orissa. 

For more eligibility and related queries you can visit below link :

https://engineering.careers360.com/articles/ojee-eligibility-criteria

Hope this will help!