This is the powershell to disable MDS in all sites and sub-sites within a web application
$webApp = Get-SPWebApplication http://sp2010
$siteCollection =$webApp | Get-SPSite -limit all
foreach ($site in $siteCollection)
{
$webs = $site | Get-SPweb -limit all
foreach ($web in $webs)
{
$url = $web.URL
write-host "Web URL = " $url -foregroundcolor "blue"
Disable-SPFeature -Identity "87294c72-f260-42f3-a41b-981a2ffce37a" -url $url -Confirm:$False
}
}
All you need to do is edit the URL to your web application from http://sp2010
Cheers,