Most users want ClipMate to capture everything, all the time. However, some users don't want that. So there is the option to turn off the AutoCapture (TEMPORARILY) under the Edit menu, and the System Tray menu. That makes ClipMate ignore new clips. But it gets reset when ClipMate restarts.
But there is a way to make it start with the setting "off". Under Tools | Options | Capturing, there is an option to "enable auto-capture at startup". This is normally CHECKED, meaning that it will start auto-capture when ClipMate starts. If you want to disable autocapture at startup, turn this option off, and re-start. Now you'll have a red "no" symbol imposed on the ClipMate icon in the system tray, indicating that ClipMate is set to NOT capture. Also, you'll hear the "rejected" sound when you copy things to the clipboard. If you don't want that sound to play, turn it off in Tools | Options | Sounds.