Here my piece of code from your snippet to remove all XWiki.Notifications.Code.NotificationFilterPreferenceClass object on all xwiki user
#if ($request.confirm == '1')
#set($className='XWiki.Notifications.Code.NotificationFilterPreferenceClass')
#set($hql = "select obj.name from BaseObject obj where obj.className='XWiki.XWikiUsers'")
## display 10 users
## set($results = $xwiki.search($hql, 10, 0))
#set($results = $xwiki.search($hql))
#foreach ($User in $results)
## * [[$User]]
## if you have more than one object on a page, you will have to loop over them and use "$doc.use"
#set ($targetDoc = $xwiki.getDocument("$User"))
#set ($result = $targetDoc.removeObjects("$className"))
#if ($result)
#set ($discard = $targetDoc.save('Removed all xobjects'))
* XObjects $className removed on [[$targetDoc]]!
#else
## Error: XObjects not removed on [[$targetDoc]] or object missing!
#end
#end
#else
----
[[**SUPPRESSION** des objets XWiki.Notifications.Code.NotificationFilterPreferenceClass de tous les utilisateurs>>||queryString='confirm=1']]
#end