Best way to approach chopta is to take bus from Rishikesh to Baijnath. It's almost a day journey. Next day take bus or taxi from Baijnath to chopta which is around 30 km away. There is one bus only. but chopta Chandrashila track can b completed till then same bus arrives back.
Take a bus from Delhi to Rishikesh or you can opt for Janshatabdi from Delhi to Haridwar. then from Rishikesh to Ukhimath and then from Ukhimath you can hire a cab to Chopta.