Did you delete it in desktop mode? Probably if you think they are still in trash. There is a folder in your home directory called .Trash (dot trash) You can view it with ls -la in your home directory /home/username
Delete the files that this directory contains and you will be free with disk space.
You can delete them by entering this directory and doing a rm -rf *
or you can
rm -rf /home/username/.Trash/*
In both cases you will delete all the files in your trash folder.