First you have to go delhi to Rishikesh stay one day in Rishikesh or by flight to Dehradun.
On next day take shared taxis to sonprayag Kedarnath. If you are with family you can take private taxi.
Pre booked your hotel at Rishikesh son Prayag and Kedarnath it’s very difficult get hotels dharamshala in Kedarnath due to Season . Next day you can go Kedarnath either by foot or by helicopter (phata-Kedarnath).it will take one or half day trek depends upon your strength. Then come back next day back to Rishikesh.
Located in the Himalayas. Kedarnath is situated at an astonishing height of 3584 meters above sea level near the head of Mandakini River. The Kedarnath temple lies amidst the majestic snow-capped Garhwal Himalayan ranges.
https://www.euttaranchal.com/tourism/kedarnath.php