Ubuntu is based on Debian GNU/Linux distribution, thus it uses Apt package manager.

Default behavior is to keep downloaded software packages on the file system during installation process. During time the packages can use a lot of disk space and we suggest occasionall cache cleaning.

How to clear Apt cache

1) Run file manager (e.g. Nautilus) as root user

2) Navitage to /var/cache/apt/archives

3) Delete all .deb installation package files

Note: Be sure not to delete folder partial and file lock.