Archive Document then Delete.

Go to your Documents App

Select Folder and document that you want to delete. When you select a document, at the right side window an Archive button appears called Archive. Click the Archive button, your document will disappear and go to archive state.

But if you want to physically delete the document, then go to Documents > Folder > Filter > Archived.

It will show your archived documents. Click on a document you want to delete, on right side a delete button will appear. This is how you can delete a document.