Logic Pro X: Trim audio regions in the Audio Track Editor
You can trim an audio region in the Audio Track Editor to remove part of the beginning or end of the region.
Trim an audio region
Place the pointer over the lower-left or lower-right edge of the region.
The pointer changes to a trim pointer.
Drag the pointer to remove the part you want to trim. As you drag, the help tag shows the region length and the amount by which it is trimmed.