If you're done with an object, you can lock it by selecting it in the object explorer under the timeline and clicking the lock. This way, the element won't get in your way as you finish up other aspects of the video.
If you're working with a template and want to unlock everything to have complete editing control, select "unlock all" after you click the lock and "lock all" after you finish.
You can also hide or show elements by clicking the eye. Once you have locked or hidden an object and want to unlock it or show it, you can select it again from the Object Explorer