First of all you have to go to https://tafcop.dgtelecom.gov.in website.
Here you have to request for OTP by giving your mobile number.
A 6-digit OTP will be sent to your mobile.
Enter it and validate it.
On the next page you will be shown all the mobile numbers registered with Aadhar number.
Apart from this, if you think about a SIM that it is not yours, then to get that SIM turned off, you will have to tick mark in front of that number on the website. After this, you will have to report for that number.