Click here to read a ChromeUnboxed article called "How To Change The Default App For Opening Different File Types On Your Chromebook" that explains the default workings of the "Files" App and how you can use it 'as is' or modify it to access your stored files in different ways.
Click here to learn how to switch on a flag that will provide you with a safety mechanism, similar to a Trash Can, that will add a new folder to the view within File Manager App from which you can retrieve [or permanently delete] any discarded files.
Without this safety belt whenever you delete a file it's gone - period - you have been warned.