At the top of the document list press the Select button (which will reveal more options at the bottom of the document list), tap on the files and/or folders to select the ones you want to delete, then press the Trash button at the bottom.
At the top of the document list press the Select button (which will reveal more options at the bottom of the document list), tap on the files and/or folders to select the ones you want to delete, then press the Trash button at the bottom.