Hello , 

As your query is you where allotted a college in second round of counselling but you don't want to join it and you want to quit the process further if you want to continue with the counselling process you can left leave the seat and go for the for the rounds of counselling and if you don't want to go with the rounds of counselling then you need to write an letter to the counselling centre and let them know that you are want to exit the counselling process once they will verify your letter they will automatically remove your name from the counselling process and then you can take your counselling fee back.
Further if you need any other detail regarding the same you can let me know in the comments section below we will definitely help you with that.
I hope your query is solved.
Thank you.