This first method will use the Audio Mixer's Fast Menu:
Using this method does not require you to display Volume or Pan Automation (though you may), while the second method, in the There's more... section, does require it.
This first method is used to remove multiple keyframes only. The second method, in the There's more... section, allows you to remove either a single keyframe or multiple keyframes.
Set the Audio Mixer to the Automation (Auto) setting rather than the Clip or Live setting.
Enable the Track Selector(s) for the track(s) from which you want to remove/delete keyframes.
This step is optional: Mark In and Mark Out around a portion of one or more segments in order to define a range (or...