Hot to delete all with one click...

As to what you are seeing in your Documents folder and how they got there...I don't know..I expect certain types of files end up in the Documents folder by default

Be careful and really look over everything in any folder before you trash things...but to simplify deleting all the various items...pick one and single click on it to highlight it...then go up to the Menu bar at the top of the screen...select 'Edit'...scroll down and click 'select all'...then back up to the Menu bar...click 'File'....click 'Move to Trash'....empty the trash...but again be sure of what you are getting rid of first..

You clicked "All Documents" in the Search section of the Finder? If so, those documents are not in one specific folder but are the result of the search of documents in all the folders of your Mac.

The way to delete them with one click is by clicking on the first document in the list and holding on the Shift key and clicking on the last document of the list. This allows you to select the whole list. If you want to exclude one (or many) document of the list from deletion, click on it while holding the Command (Cmd or Apple) key. You can also do this to select documents among the list.