Hello to you all.

I'll get straight to the point. I am using the newest version of windows movie maker but I noticed that if I attempt to move or delete any clips used in my project (As in original clips), that section gets deleted from my edited project. For example, if I were to get a clip of a video footage and used that in my project but edited out half of it and later attempt to delete the original one to free up space, my edited clip in movie maker gets deleted as well. I never knew the two were still connected even if it was now used in another software. Is this normal or is there any way to fix it because of as of now, my desktop is full of clips that I want to free up. Any help appreciated, thanks in advance! 

<Original title -Movie Maker  >