Cant delete documents and data on icloud

On your iPad, have you gone into Settings > iCloud > Manage Storage > Documents & Data [select the app e.g. Pages] > Tap Edit [top right] [select red circle and delete]?

You should have an Edit option. According to Apple for iOS 5 and up:

Documents in the Cloud

You can manage your stored iCloud documents from an iOS device using iOS 5 or later, a Mac using OS X Lion v10.7 or later, or a Windows computer that meets the iCloud system requirements. iWork documents for iOS apps are also available on iCloud.com. Follow the steps below to delete a document.

iOS 5 and later

1. Go to Settings > iCloud > Storage & Backup, then tap Manage Storage.
2. Under Documents & Data, tap the app from which you want to delete data. This displays any documents in iCloud for that app.
3. Tap Edit, select the item that you want to delete, then choose Delete or Delete All. The document or data is removed from your iCloud storage and from all of your devices.

Can you be clearer about the error at iCloud.com?

Not all apps data saved to iCloud can be accessed through iCloud.com