Hi Sarang,
As far as I know, we cannot directly move those email accounts to Office 365 if the current domain is still being used by live.com service, which means freeing up your domain from live.com service is the first step.
As Office 365 Online Services support engineers, we cannot help you remove the domain from live.com service. Please directly contact live.com support through the following link:
http://answers.microsoft.com/en-us/outlook_com/forum/oadmincenter?tab=Threads
Thanks for your understanding!
Best Regards,
Allen