Remove Users from Linux Groups with usermod, gpasswd, and /etc/group

Linux users belong to a primary group and optional secondary (supplementary) groups, defined in /etc/group. This guide shows three ways to remove a user from groups: the usermod command, the gpasswd command, and manual editing of /etc/group.

Creating a test user and groups

First, a test user is created, which automatically creates a primary group with the same name: $ sudo useradd -m testuser A password is set for the new account: $ sudo passwd testuser Two supplementary groups are added:

$ sudo groupadd testgroup1
$ sudo groupadd testgroup2

The user is then added to the new groups and to root:

$ sudo usermod -a -G root testuser
$ sudo usermod -a -G testgroup1 testuser
$ sudo usermod -a -G testgroup2 testuser

Viewing /etc/group confirms the memberships.

Finding a user’s groups

Two commands provide the same information:

$ groups testuser
$ id -nG testuser

Removing a user from groups with usermod

The usermod command can replace the list of supplementary groups for a user. To keep the user only in the root group (removing it from testgroup1 and testgroup2), run: $ sudo usermod -G root testuser Result:

$ groups testuser
testuser : testuser root

Multiple groups can be specified as a comma‑separated list, e.g.:

$ sudo usermod -G root,testgroup1 testuser

Removing a user from groups with gpasswd

The gpasswd -d command deletes a user from a specific group. Examples:

$ sudo gpasswd -d testuser root
Removing user testuser from group root
$ groups testuser
testuser : testuser testgroup1 testgroup2
$ sudo gpasswd -d testuser testgroup1
Removing user testuser from group testgroup1
$ groups testuser
testuser : testuser testgroup2

Manual removal by editing /etc/group

Open /etc/group with a text editor and delete the user name from the desired group lines. After editing, the relevant lines look like:

testuser:x:1001:
testgroup1:x:1002:
testgroup2:x:1003:

After saving and restarting (or re‑reading the file), the user is removed from those groups:

$ groups testuser
testuser : testuser root

Conclusion

The tutorial demonstrates how to remove a Linux user from groups using usermod, gpasswd, and by directly editing /etc/group. These commands work on any Linux distribution such as Ubuntu, CentOS, or Fedora.