There is a problem after the version of Totara1.1.The version before Totara1.0.x doesn't have it.
If you want to delete the pictures that have been uploaded while you scan pictures by click [Insert / Edit Picture] button in html editors, you will find that the select picture is not deleted after the page refreshes .
The Debugging found it's a Totara bug.
Solution is:
Modify the file : \lib\editor\tinymce\coursefiles.php 574 line
if (file_exists ($ basedir. $ clean_val))
Changed it to
if (file_exists ($ basedir. '/'. $ clean_val))