Ubuntu 12.04 comes with a very simple “User Account” option that doesn’t really provide you with much options. If you are looking to add user to a group, such as adding yourself to the “vboxusers” group so you can enable the USB drive support in Virtualbox, you won’t be able to do so with any default application. Here is how you can do so.
1. Command Line
The first method is via the command line. To add a user to a goup, open a terminal and type:
sudo usermod -a -G group username
Replace the “group” with the group that you want to add to.
Replace the “username” with the name that you want to add to the group.
To remove a user from a group, you can use the following command:
sudo deluser username group
Note that you have to specify the “Group” in the above command. Failure to do so will result in the removal of the user instead.
2. Gnome System Tools
If you prefer a GUI over the command line, you can make use of the gnome-system-tools app to manage your users.
sudo apt-get install gnome-system-tools
Once installed, launch the “Users and Groups” application.
Click the “Manage Group” button.
Scroll down to find the group that you want to add/remove user. Highlight it and click Properties.
Check/uncheck the username to add/remove users.