Files and folders that are deleted will be in the Trash folder and still counting towards your quota until they are permanently erased, as shown below:

Step 1: From the navigation drop-down menu, touch the “Trash” option.

Step 2: Touch the action icon for the file/folder you want to permanently erase.

Step 3: From the action menu touch the “Erase” option.

You will see a message that the file/folder is now permanently erased.