How Can I delete portions of a Video and a separate audio track together in iMovie?

The following scenario:

You do have a video-clip and an added, separate audio-track - but you need to 'cut out' a piece in both, of same length, at same position (e.g. to keep a narration in synch with pictures).

What we do is a sort of setting In/Out-points, to split the clips into A/B/C, and then delete B:

set playhead at beginning of to-be-deleted part; most probably, you do make the video-clip 'active' (yellow border). If not, click once into it.

hit cmd-shift-s on your keyboard; this will split the clip into two

keep playhead at position!

(hint: zoom into timeline, by pushing the slider, lower right to the left)

Another Hint to keep playhead in position:

Hold down the Control Key while clicking on the Audio Track. This will keep the playhead in the same position.

So, Control-click into the audio-track; cmd-shift-s; audio-track and video are now split into two parts.

repeat for end of to-be-deleted part

the clips are now split into A,B and C

finally, click into the middle video-clip (B) and hit backspace to delete - poof! gone.

The audio-clip was connected to the video-clip, so it will vanish, when you erase the video.-

As you see in the screen-shot:

iMovie notices in the Event-Browser, that the middle-part is not in use anymore.

Happy Movie Making! 😁

(clips from 'Plan 9 from Outer Space', which is in the Public Domain)