As per the FAQ section of UPSC official website:

• There is no editing facility in the application. In case of any mistake in filling application, candidate is responsible. However, fresh application may be made for correction of earlier mistake.

Now the question is What should you do if you have done mistake then the answer provided is:

• Most of communications to candidates are carried out online by UPSC and address is hardly a matter in this regard. Please ensure your email-id & Mobile No is active.

For more FAQ's you can follow the link below:

https://upsconline.nic.in/upsc/faq.php#:~:text=There%20is%20no%20editing%20facility,for%20correction%20of%20earlier%20mistake.&text=The%20system%20allows%20you%20to,by%20using%20the%20Update%20button.

To know more about UPSC you can visit the link below:

https://competition.careers360.com/exams/upsc-civil-services-exam

I hope this answer helps. All the very best for your future endeavors!