Not able to register into income tax portal due to mobile number issue

I am trying to  register to file my tax return in income tax site. When I do that I am getting This number is already used for 5 PANs.You cannot use same Mobile for more than 5 users. I want to remove my mobile number from those PAN and use that mobile number for my login, please help me on this.

This 5 PAN may be linked when I work in previous Auditor office Long back

Thanks.