how to delete .trash/.trashes files?

I have a 16 GB iPhone 5s, and I started getting the "storage almost full" message. I have about 300 songs, 700 photos, and 22 total apps. I went to iTunes on my computer, and it says that I have 1.3 GB "Other" and 2 GB free. I suspect this discrepancy to be caused by .trash/.trashes files (pesky little buggers), but I'm not sure how to delete them. I'd like to avoid restoring my phone if possible. Thanks for any help.