As per CBSE guidelines, a student can opt for a change in subject upto October 30th while he/she is in class 11 only. Change of subject to a new subject for which the student has not studied in class 11 will not be permitted in class 12.

But as i can see you had Physical Education in class 11 but due to an error your school has submitted Computers as your 5th subject. You may write an application and get it signed by your pricipal and send it to the CBSE Zonal office of your place/state, clearly stating your condition and the error in subject selection. Since you havent studied computers in class 11, your case would ideally be considered and your subject may be reverted back to physical education.