Samsung Galaxy S5 SD card Write Protected?

[AC Question]

So I connected my Samsung Galaxy S5 to my pc with a USB cable. I then tried to delete a folder inside the Music folder. Then I got this error message;

Error Deleting Folder. Cannot Delete AC_DC: The Storage is write protected. Please remove the write protection and try again.

? I have skimmed some forums here already but this is the first time ive ran into a problem like this.

Thanks