How to uninstall libegl1-nvidia-legacy-340xx from Ubuntu
To uninstall just libegl1-nvidia-legacy-340xx package itself from Ubuntu execute on terminal:
sudo apt-get remove libegl1-nvidia-legacy-340xx
Uninstall libegl1-nvidia-legacy-340xx and it's dependent packages
To uninstall the libegl1-nvidia-legacy-340xx package and any other dependant package which are no longer needed on Ubuntu.
sudo apt-get autoremove libegl1-nvidia-legacy-340xx
If you also want to delete configuration and/or data files of libegl1-nvidia-legacy-340xx from Ubuntu then this will work:
sudo apt-get purge libegl1-nvidia-legacy-340xx
To delete configuration and/or data files of libegl1-nvidia-legacy-340xx and it's dependencies from Ubuntu then execute:
sudo apt-get autoremove --purge libegl1-nvidia-legacy-340xx
libegl1-nvidia-legacy-340xx package information
NVIDIA binary EGL libraries (340xx legacy version)
More information about apt-get remove
Advanced Package Tool, or APT, is a free software user interface that works with core libraries to handle the installation and removal of software on Debian, Ubuntu and other Linux distributions. APT simplifies the process of managing software on Unix-like computer systems by automating the retrieval, configuration and installation of software packages, either from precompiled files or by compiling source code.
apt-get is the command-line tool for handling packages, and may be considered the user's "back-end" to other tools using the APT library.
apt-get remove is identical to install except that packages are removed instead of installed. Note that removing a package leaves its configuration files on the system. If a plus sign is appended to the package name (with no intervening space), the identified package will be installed instead of removed.