Yes, you can do correct mistake in IIT JEE application form but only once.

Instructions and procedure for Correction in Application Form Particulars of JEE Main :

All the details (Except city for Examination and mode of examination from computer based examination to pen and paper based examination) in Application Form are editable.

Correction in Application Form Particulars will be allowed only once.

After correction in the Application Form particulars, change(s) will be updated immediately.
if additional Examination Fee is not required based on the changes in particulars.

In case additional Examination Fee is required to pay based on the changes in Application Form then final updation of correction in Application Form will be done only after the successfully payment of additional amount of Examination Fee.

Additional amount of Examination Fee (if applicable) may be submitted either by any Credit/Debit card or through e-Challan of Syndicate Bank/Canara Bank/ICICI Bank/HDFC Bank.