When you are a half-op or above you have channel control options available. You can click on a user to control various aspects.
Access Levels - Depending on your access level you'll only be able to grant certain access. (Voice, Half-Op, Op, Admin)
Kick from Channel - Kicks/forces the selected user from the channel
Ban from Channel - Bans and prevents user from rejoining channel until ban is removed. Does NOT remove the user from the channel.
Ban and Kick from Channel - Bans and forces the user out of the channel.

Additional Channel Management:
Click the Gear Icon top right corner for channel settings.
Settings Tab - Gives you the ability to set a topic, moderate, set channel to invite only, set a channel password, as well as various other options.
Access Tab - Allows you to control banned users and manage invites specifically set.
Notifications - This is a PERSONAL setting. Allows you to control notifications