Is the whole drive right protected, or just some folders?
1) Right click the drive and go to properties.
..Select Security tab
.. Then select Advanced and under permissions doble click the "allow"
.. Make sure there is a check mark for (or check it).
...... Create files/write
...... Create folders
...... Writte attribuites
...... Heck, just check All of them!!!
If that does not work, then check the manuf web site for tools to perform a secure erase.
Also For example: Sandisk drives often come with U3 utilities to delete these go to sandisk and get utility do delete them.