Filled non-assessee by mistake

Hi members,

By mistake I filled up non-assessee form at aces.gov.in for service tax registration.

But my company comes under service tax assessee and I am not getting any option to fill form ST-1.

Now, how can I fill up form ST-1 and get a service tax number? I want to remove my company from non-assessee.

Thank you in advance for your help.