You may not remove the primary group of any existing user. You must remove the user before you remove the group.
You should manually check all file systems to ensure that no files remain owned by this group.
The following configuration variables in /etc/login.defs change the behavior of this tool:
The default value is 0, meaning that there are no limits in the number of members in a group.
This feature (split group) permits to limit the length of lines in the group file. This is useful to make sure that lines for NIS groups are not larger than 1024 characters.
If you need to enforce such limit, you can use 25.
Note: split groups may not be supported by all tools (even in the Shadow toolsuite). You should not use this variable unless you really need it.
The groupdel command exits with the following values:
chfn(1), chsh(1), passwd(1), gpasswd(8), groupadd(8), groupmod(8), useradd(8), userdel(8), usermod(8)