HI HM Yoong,
There still don't have the direct official LPC43xx pinmux tool now, we also recommend you use the
A 3rd party LPC43xx Pinmux tool
This Pinmux tool is for the LC43XX, you can try it.

If you still have question, please contact me!
Have a great day,
Kerry
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------