Have you tried with sudo?
Below is an example of how I removed a partial download in Debian as root from the command line:
Code:
fox:/var/cache/apt/archives/partial# ls
acm_5.0-27_amd64.deb
fox:/var/cache/apt/archives/partial# rm -f acm_5.0-27_amd64.deb
fox:/var/cache/apt/archives/partial# ls
fox:/var/cache/apt/archives/partial#
In your case, because you use Ubuntu, you need to use sudo as such:
Code:
fox:/var/cache/apt/archives/partial# ls
acm_5.0-27_amd64.deb
fox:/var/cache/apt/archives/partial# sudo rm -f acm_5.0-27_amd64.deb
fox:/var/cache/apt/archives/partial# ls
fox:/var/cache/apt/archives/partial#
If for some reason Ubuntu's security measures won't let you do it as a user, try as admin. by switching to admin. with command:
su -, then try again.