You "icloud" what?
iCloud Backup? You can't delete anything from that. You can only delete the whole backup.
iCloud Drive? Open the app and delete what you want to delete.
iCloud Photos? Just delete the photos from your device or log in to iCloud.com on a computer and delete what you want to delete.
iCloud Notes? Open the app and delete what you want to delete.
If you provide more details of your situation, then more detailed assistance can be provided?