Remove i:0#.w from UserName using powershell

HI,

I converted the windows based 2010 sharepoint application to claims based sharepoint 2013 application.

How to change the "i:0#w|domain\username" to "domain\username" for all the users using powershell.

Note: I do not have user profile service application running.

Is it possible to convert the names for all the users using powershell.

Thanks