Deleting file created from mysql
The file's owner group is mysql. Please use the id command to find out another user of that group and try deleting it. It appears that the user ID you are using to delete the file may not have write access on tmp directory.
Are you able to truncate the contents of the file? Please do this only if you don't want the results.out file in /tmp/
echo " " > /tmp/results.out
You could always just overwrite the file the same way you created it with something small and harmless.
It is common practice on unix systems to clear out /tmp/* on reboot, so it won't stay there forever either.