I am having the same problem.
I couldn't delete anything from the drive. After quite a while I decided that I should just format and start over. Then I found out that I can't format it for the same reason (Disk is write-protected). I then used the "erase disk" function from the WD Passport management software. When I did that, the disk was no longer recognized by the WD software and when I tried to look at the drive through windows, it told me that it wasn’t formatted. I tried to format it but it still says that it is write-protected.
I also noticed one other thing. The light is blinking constantly.
Does anyone have any ideas?