Delete all SPWeb objects that are not provisioned.

Remove-NonProvisionedSPWeb.ps1

Add-PSSnapin Microsoft.SharePoint.PowerShell

# get all webs that are not read locked, not provisioned and created more than 5 minutes ago (so we don't delete anything that might be in the middle of provisioning)
$unprovisionedWebInfo = Get-SPSite -Limit All | ? { -not $_.ReadLocked } | Get-SPWeb -Limit All | ? { -not $_.Provisioned -and $_.Created.ToLocalTime().AddMinutes(5) -lt (Get-Date) } | SELECT URL, Created, WebTemplate, Provisioned, IsRootWeb

# write the data to csv for record keeping
$unprovisionedWebInfo | Export-Csv -Path "E:\UnprovisionedWebsToDelete.csv" -NoTypeInformation 

foreach( $webInfo in $unprovisionedWebInfo )
{
    # make sure the web still exists, it could have been deleted if it was a sub to a rootweb that was deleted.
    $webExists = Get-SPWeb -Identity $webInfo.Url -ErrorAction SilentlyContinue

    if( $webExists )
    {
        if( $webInfo.IsRootWeb )
        {
            Write-Host "Deleting Site: $($webInfo.Url)"

            # delete the entire site since the rootweb is not provisioned
            Remove-SPSite -Identity $webInfo.Url -Confirm:$false
        }
        else
        {
            Write-Host "Deleting Web: $($webInfo.Url)"

            # delete the subsite
            Remove-SPWeb -Identity $webInfo.Url -Confirm:$false
        }
    }
}