I am sorry, I don't think it's possible to change the number. However you should try calling the helpline once. 

Dear Abhay,

NEET correction dates are start from 15th March from 10:00 AM. 

You can edit your application form by logging into your account. 

Good Luck!!

Sorry you can't change your phone number.

Correction window open , but i think changing phone number not possible. Try calling the helpline once

https://cbseneet.nic.in/cbseneet/ShowPdf.aspx?Type=E0184ADEDF913B076626646D3F52C3B49C39AD6D&ID=572E20738130FDDC7C389F2AB14F4E4B22A97C3

Please visit this link to do the corrections

https://www.neet2018nic.co.in/neet-2018-form-correction.html