Steam, a digital distribution service for PC games, is more than just a storefront. Steam community features include a friends list, text and voice chat, and the ability to make and join groups. Members can use groups for a number of reasons, such as for clans, groups of people who play the game together. If you are the administrator of your group and no longer wish to have a member in it, you can kick that member out of your group from within Steam.
Launch the Steam client.
Select the "Community" link, then click on "Groups."
Click "Visit Admin Page" next to your group, then select the link for "Manage Members."
Click the red "X" next to the name of the member you wish to remove. That member will now be deleted from the group.
Only the administrator of a private group can kick members out -- public groups have no option to kick members.