There's several ways to reduce the bass response of that part of the circuit, some will have a greater effect than others. Changing C9 to a lower value, like .1uF or less will greatly reduce the bass response. Changing C7 to a lower value like .047uF will have a less prominent effect (maybe not even really noticeable). Reducing C8 to something like .47uF will have a pretty dramatic effect too. Removing C10 or lowering the value will allow more high end content to move to the next stage. Sometimes it's not so much "too much of this range of frequencies" as it is "not enough range of these other frequencies". You could also parallel R13 with a small value cap to bleed more treble to the next stage as it and R14 are working as a voltage divider sending a good deal of the signal to ground. Something like 470pF or 270pF or even lower like 100pF or 47pF might be enough. Every circuit is different and sometimes all you need is a little bit of highs to "lift the blanket" so to speak.
