If you want to delete blurry close-ups, accidental shots, or something else from your video project, you’re in luck. Using Apple iMovie, you can trim unwanted frames from your project clips. All you have to do is select the clips you want to trim and choose Edit→Trim to Selection, and the unwanted frames in your movie are deleted.
You can bring back deleted frames by adjusting the clip’s duration or frame range as follows. Select the clip and then choose Edit→Trim (or click the Clip Duration icon, which resembles a clock and appears in the bottom-left corner of the clip). Your selected clip appears in a trimmer, with start and end handles you can drag at either end.
You can also
Move the start or end point frame by frame: Hold down the Option key while pressing the left or right arrow key, respectively.
Move the entire frame range selection frame by frame in the direction you indicate: Press the left or right arrow key, respectively, without holding down Option.
Adjust a clip one frame at a time, without using the trimmer: Move the mouse pointer to the end of a given clip and hold down the Command and Option keys. Drag the orange handles that appear to the left or right to lengthen or shorten a clip duration, respectively, one frame at a time.
Extend or shorten a clip a frame at a time, again without using the trimmer: Move the pointer to the end of the clip and hold down the Option key while pressing the left or right arrow key.
Click Play in the trimmer to preview your efforts and click Done when you’re satisfied with the results.
To quickly preview one second of video before and one second of video after the point where the change was made, place the mouse pointer at the spot where you’ve made your edit and then press the left bracket key. Or press the right bracket key to play three seconds of video before or after that point.