If you have delete privileges,
you will see the Delete Icon for
each file. Click the icon to delete the file, and then click Yes
in the confirmation dialog box. To delete a group of files, select the
check box for each file you want to delete and click the Delete Checked
Files icon located at the top of the thumbnails panel.
Files that contain markups cannot be deleted, regardless of the delete permission, unless configured by the system administrator to allow.