Don is correct in that you should check out the -recurse to look through the entire drive. You should also use -include to include only those file types you’re looking for.
Here’s an example of EXcluding certain file types from a search. (This particular script looks for and removes files older than 6 years, excluding certain file types)
The -Whatif at the end tells powershell to only simulate the command, and not actually remove any files. I generally use that when I am testing scripts that delete data.
$strDRV = Read-Host 'Enter Drive to Remove Aged Data From: Ex: C:\ '
Get-ChildItem $strDRV -exclude *.exe,*.mdb,*.dbf,*.ndx -recurse| where {!$_.PSIsContainer -and $_.Lastwritetime -lt (date).adddays(-2190)}|remove-item -force -WhatIf