Select the Secured Space you want to edit and click on Edit from the options shown.
Double click the checkbox associated to the Secured Space you want to delete.
Your space and all the files in it will be deleted after you agree to the confirmation message.
Select the files you want to move and click on Edit.
Select the Secured Space you want to move your files to and click on Save.
To delete files belonging to the same Secured Space, select them and click on Delete.
Your files will be deleted once you agree to the confirmation dialog.