Can't execute sudo apt-get update / upgrade

Question

When i try to execute sudo apt-get update i receive the error:

W: The repository 'http://linux.teamviewer.com/deb preview Release' is not signed. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details.

My /etc/apt/sources.list contains:

deb http://mirrordirector.raspbian.org/raspbian/ jessie main contrib non-free rpi
# Uncomment line below then 'apt-get update' to enable 'apt-get source'
deb-src http://archive.raspbian.org/raspbian/ jessie main contrib non-free rpi
deb http://mirrordirector.raspbian.org/raspbian/ stretch main contrib non-free rpi

And /etc/apt/sources.list.d/raspi.list contains:

deb http://archive.raspberrypi.org/debian/ jessie main ui
# Uncomment line below then 'apt-get update' to enable 'apt-get source'
#deb-src http://archive.raspberrypi.org/debian/ jessie main ui
#deb http://mirrors.ustc.edu.cn/archive.raspberrypi.org/ jessie main ui

Any Sugestions? Obs: I have TeamViewer installed and i try to remove it but i can't how i do this?

Answer 1

apt-get remove <package_name>

This command removes an installed package, leaving configuration files intact.

apt-get purge <package_name>

This command completely removes a package and the associated configuration files.

Type apt-get without any option too see all options available.