Windows Powershell Rename Column Heading CSV file

You may use Select-Object with a calculated property to do this.

 Import-Csv test.csv |
     Select-Object @{ expression={$_.first_name}; label='test' } |
         Export-Csv -NoTypeInformation test1.csv

Can't you try something like :

import-csv 'c:\tmp\test.csv'  | select -Property @{name="test";expression={$($_.first_name)}}| Export-Csv c:\tmp\test1.csv