Hello,

In NTA NEET UG 2021 Information Bulletin it is clearly mentioned in page no: 2  if a candidate fills and submit more than one application, the Admit Card of the applicant will be cancelled or withheld and his/her candidature will be cancelled for this/future examination. As your brother has submitted multiple application his candidature may get cancelled. A candidate can select 4 cities in the order of preference in one application, so one application is enough by selecting the cities he prefer in the order of preference. He would be allotted one exam center among the selected cities. There is no provision to cancel or withdraw the application for NEET UG 2021, we regret to inform you that he cannot do anything about it now.

You can go through the information brochure using the link below

https://neet.nta.nic.in/webinfo/File/GetFile?FileId=83&LangId=P