deleting managed metadata using powershell script sharepoint 2010

Question

Deleting managed metadata term stores using powershell script. Was trying with the below script but getting error "Cannot index into null array". Please help out thanks in advance....

Add-PSSnapin Microsoft.SharePoint.Powershell
Clear-Host
$taxonomySite = get-SPSite "http://"
$mmsServiceName = "Managed Metadata Service"
#$taxonomySite = Get-SPSite $centralAdminURL
$taxSession = Get-SPTaxonomySession -Site $taxonomySite
$termStore = $taxSession.TermStores[$config.configuration.configSettings.mmsServiceName]
$grpName = "XXX"
$grpManager = ""
$termSetName = ""
$termSetOwner = ""
$tsStakeHolder = ""
Clear-Host 
$group = $termStore.Groups["XXX"]
if ($contentsource -ne $null)
{
    $contentsource.Delete()
}

if ($termStore -ne $null)
{

    if ($group -ne $null)
    {
        $group.TermSets|foreach{
            $_.Delete()
            $termStore.CommitAll()
        }
        $group.Delete()
        $termStore.CommitAll()
    }
}

Answer 1

After spending sometime found the solution just need to mention the terms

#Script for deleting managed metadata 
#Calling Taxonomy site and group Name
Add-PSSnapin Microsoft.SharePoint.Powershell
Clear-Host 
$taxonomySite = get-SPSite "http:" 
$mmsServiceName = "Managed Metadata Service"
$grpName = "XXX"
$grpManager = "YYY"
$termSetName = "XXXX"
$termSetOwner = ""
$tsStakeHolder = ""
$centralAdmin = "XXXXXX"
#$termsetName = "VVV"
#$grpName = "XXXX"

        $site = Get-SPSite $centralAdmin
        $session = new-object Microsoft.SharePoint.Taxonomy.TaxonomySession($site)
        $termStore = $Session.TermStores[$mmsServiceName];
        $group=$termStore.Groups[$grpName]
        $group.TermSets|foreach{
            $_.Delete()
            $termstore.CommitAll()
        }
        $group.Delete()
        $termstore.CommitAll()

        Write-Output "Deleted $groupName"