Play the audio to decide where you want to cut or split it.
Drag the playhead at the position where you want to cut or split it.

Split
Click on the split icon above timeline to split the audio clip.
Or click on edit menu click on split clip.

Click on the audio part which you want to delete & hit delete key to declare it.

Cut
To cut the clip drag the playhead where you want to cut the clip. Split it.
Select the part by clicking on it and hit Ctrl+x keys on keyboard

Trim
Take mouse pointer on left edge of audio when mouse pointer changes in two headed arrow.
Drag it to right side to trim the audio.

Same way you can trim the audio from right side