You can disable clips placed on the timeline. Disabled clips cannot be played back.
1) Right-click the clip to disable, and click [Enable/Disable].
Disabled clips are displayed in gray regardless of their type.
Select the clip to disable, click [Clip] on the menu bar, and click [Enable/Disable].
Enabling/disabling clips: 
You can enable disabled clips by the same operation.
Disabled clips can be edited in the same way as enabled clips.