If you have files in your hosting package that you cannot remove, you can consult this article to fix this.
In this article, we assume that you're already logged in to DirectAdmin.
To this end, you must go to the filemanager. Click the button Files at the top in DirectAdmin.
then click the folder domains, and then your own domain.
Select public_html, see number 1 in the image below. Click recursive, see number 2. Then click "Reset Owner", see number 3.
If you do this, you will receive the following notification. After this notification you can remove the files and / or folders.