How to remove/edit slow motion

I accidentally recorded videos on I-phone6 using slow motion. I can see the slide bar to remove it when I view the video but cannot save it. I sent it to my laptop using Air Drop and again, it shows in slow motion. I used Quick Time to remove it (by sliding the bars at the bottom) and saved it but when I re-open the file, the slow motion is active again. I tried to export, to duplicate, etc. but I cannot remove the slow motion somehow. I would remove the slow motion as soon as possible.