Remove links from the quick launch in classic SharePoint Team sites. See https://jcallaghan.com/2011/10/clear-the-sharepoint-quick-launch-using-powershell/ for more information. #Website

Remove-SPQuickLaunchLinks.ps1

function Remove-SPQuickLaunchLinks{
  Param(
    [parameter(Mandatory=$true)]
    [String]
    $url
  )
   
  $SPWeb = Get-SPWeb $url
  $QuickLaunch = $SPWeb.Navigation.QuickLaunch
  $Nodes = @()

  $QuickLaunch | ForEach-Object {
    $Nodes = $Nodes + $_.Id
  }

  $Nodes | ForEach-Object {
    $Node = $SPWeb.Navigation.GetNodeById($_)
    $Node.Delete()
  }
  $SPWeb.Dispose()
}

Remove-SPQuickLaunchLinks -url "https://sharepoint.jcallaghan.com/"