Ubuntu, a GNU/Linux distribution based on Debian, uses Apt package manager to install, uninstall and update applications and their requirements.
During the installation process, Apt by default keeps downloaded packages on the file system. It can use a lot of disk space so I recommend to occasionally clean the software cache on your Ubuntu system.
How to delete 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.