NWZ 615F Blk MP3 player (by 2 users)

I have a Sony NWZ 615F Blk MP3 player. I loaded songs into the music folder and had to reset the player. When I went back to reload the songs, of course they were not there. But I couldn't add any songs either due to it saying it was full. But nothing is on the MP3 Player. The storage is saying 1.71 GB. How do I clear the memory/storage so I can add songs back on to the player?