# why dnf remove is not working

i know that this question has been asked before and i am sorry for asking it again but i didn't undersatnd the answer i want to UN-install virtual box from fedora 26 but when i put the following command sudo dnf remove packagename , it shows the following error

Traceback (most recent call last):
File "/usr/bin/dnf", line 58, in <module>
main.user_main(sys.argv[1:], exit_code=True)
File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 179, in user_main
errcode = main(args)
File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 64, in main
return _main(base, args, cli_class, option_parser_class)
File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 99, in _main
return cli_run(cli, base)
File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 115, in cli_run
cli.run()
File "/usr/lib/python3.6/site-packages/dnf/cli/cli.py", line 1010, in run
self._process_demands()
File "/usr/lib/python3.6/site-packages/dnf/cli/cli.py", line 763, in _process_demands