Hi Kristian

I think that the file type is referring to the file extensions and what format the file is and what to do with the file. (MIME type)

So a file with the extension pdf might have a MIME type of application/pdf which means I need to launch the associated PDF program that the user has installed and it’s registered as the application/pdf handler”

If you deleted the file type this deletes the action that takes pace when a pdf file is encountered ratherthan preventing the file being uploaded.

To control the upload of files for assignments go to the Assignment settings > Accepted file types and add the file extensions you want to allow including .pdf

The file may also not be uploaded as there is an upload file size limit on the course or activity

Regards