If you already have mobile number linked to your Aadhaar and you wish to update it with the new mobile number, you can do the same as follow -
1. Visit the Aadhaar portal https://ask.uidai.gov.in/#/
2. Enter your registered mobile number or email id and also enter Captcha given before clicking on ‘Send OTP’.
3. Next enter the OTP received on your mobile number/email id and proceed.
4. Select the option you wish to change from the dropdown under Online Aadhaar Services.
5. Click on the required option and fill the details to update the registered mobile number
6. Enter your Name and Aadhaar number along with the mobile number which you wish to update with Captcha code. Once you enter captcha you will receive OTP on your registered mobile number. Post verification of OTP click on Save and proceed.
7. Finally check all the details and click on submit.
8. Next screen will show you confirmation of your application submitted with your Appointment ID. Click on ‘Book Appointment’ to book your slot at Aadhaar Enrolment Centre.
Once this process is completed you need to visit Aadhaar Seva Kendra nearest to your place.