Instructions
Go to the "Music" section of your Cross Media Browser, or XMB. Select a song that you want to delete and press the "Triangle" button to open its Options menu. Select "Delete," then click "Yes" to confirm. Delete all songs that you no longer listen to.
Open the "Video" section of the XMB. Videos can take up a significant amount of hard-drive space, depending on a file's length and quality. Select a movie, press the "Triangle" button and select "Delete." Click "Yes" to confirm.
Go to the "Photo" section of the XMB and delete any photographs that you no longer need. Back-up important photographs on an external hard drive before deleting them.
Open the "Game" section of the XMB. Games purchased and downloaded from the PlayStation Store are stored on your internal hard drive. If you no longer play a certain title, select it, then press the "Triangle" button. Select "Delete." Click "Yes" to confirm. As these purchased games are still tied to your PSN account, you can re-download them from the store later.
Scroll to the "Game Data Utility" folder in the Game section of the XMB. Press the "X" button to select it. Some games store large files on your hard drive to speed up loading time. If you have a game that you no longer play, or do not play as much, select it, press the "Triangle" button and select "Delete."
Scroll to the "Memory Card Utility (PS/PS2)," "Saved Data Utility (minis/PSP)," or "Saved Data Utility (PS3)." Your game's save files are stored on your internal hard drive. Go to any game's save data that you no longer need, press the "Triangle" button and select "Delete."