Extract the filename from a path
If you are ok with including the extension this should do what you want.
$outputPath = "D:\Server\User\CUST\MEA\Data\In\Files\CORRECTED\CUST_MEAFile.csv"
$outputFile = Split-Path $outputPath -leaf
Use .net:
[System.IO.Path]::GetFileName("c:\foo.txt")
returns foo.txt
.
[System.IO.Path]::GetFileNameWithoutExtension("c:\foo.txt")
returns foo
Using the BaseName in Get-ChildItem displays the name of the file and and using Name displays the file name with the extension.
$filepath = Get-ChildItem "E:\Test\Basic-English-Grammar-1.pdf"
$filepath.BaseName
Basic-English-Grammar-1
$filepath.Name
Basic-English-Grammar-1.pdf