Format SD Card on your Android phone. It delete all data on SD Card including music and photo. To Format SD Card on Galaxy S3 and other Samsung devices do as follows:
1. Open "Settings"
2. Tap "Storage"
3. Scroll down to the end, and tap "Format SD Card"
4. Hit Format SD Card button to start deleting all your data stored in the SD Card. Note that, deleted content cannot be restored or recovered after SD Card is cleared