Find the start of the part press the I key for the in or start point
find the end of the part press the O key for the out point
then press shift+Q to select the part
then the delete key, and that piece is deleted.
If you have ripple editing enabled, and i suggest you do most of the time, it's as simple as dragging the mouse across an an empty section of the timeline or across the selection bar above the timecode display to select the section to be deleted and then pressing the delete key. If you don't have ripple editing enabled then you'll end up with a hole where the deleted section used to be.
The opposite of delete is Trim (with the T key) which deletes the part of the event outside of the selection instead of the part inside it.