Helper function to remove old module versions

Uninstall-ModuleOldVersion

function Uninstall-ModuleOldVersion {
    [CmdletBinding()]
    [OutputType()]
    param (
        [Parameter(Mandatory = $false, Position = 1)]
        [string] $Module = "*"
    )

    #Copy & pasted from the work of Jack (@sharepointjack) - http://sharepointjack.com/2017/powershell-script-to-remove-duplicate-old-modules
    #Will test all installed modules for multiple versions installed on the machine.
    #All versions that are below the highest will be uninstalled

    $modules = Get-InstalledModule -Name $Module -ErrorAction SilentlyContinue

    if ($null -eq $modules) {
        Write-Host "Unable to locate any module based on the parameter value: $Module" -ForegroundColor Yellow
        return
    }
 
    foreach ($mod in $modules) {
        Write-Host "Checking $($mod.name)" -ForegroundColor Yellow
    
        $latestModule = Get-InstalledModule -Name $mod.name
        $specificModules = Get-InstalledModule -Name $mod.name -AllVersions
        $numberFound = 0
        if($null -eq $specificModules.count) {
            $numberFound = 1
        } else {
            $numberFound = $specificModules.count
        }

        Write-Host "$numberFound version(s) of this module found [ $($mod.name) ] - Latest is: $($latestModule.version)"
  
        foreach ($specificModule in $specificModules) {
            if ($specificModule.version -ne $latestModule.version) {
                Write-Host "Uninstalling $($specificModule.name) - $($specificModule.version) [latest is $($latestModule.version)]" -ForegroundColor Yellow
                $specificModule | Uninstall-Module -force
                Write-Host "Done uninstalling $($specificModule.name) - $($specificModule.version)"
                Write-Host "    --------"
            }
	
        }
        Write-Host "------------------------"
    }
    Write-Host "Done"
}