Navigate with the Windows explorer to the directory/file which contains your confidential data.
Right click on the directory/file and choose properties from the menu
Select the Security tab and click on the button Advanced
Select the Auditing tab and click on the button Add
Click on Select a Principal
Type Everyone and click on Check Names after that click on OK
Select All and then click on Show advanced permissions
Mark List folder / read data
Mark Create files / write data
Mark Delete subfolders and files
Click on OK
Click on Apply. If there are a lot of files this may take some time
After the Apply is finished click on OK in this window and in all the previous windows.