Hi @nidhintomy,
The KW38 can be externally debugged by using MCU-Link Debug Probe (or MCU-Link Pro Debug Probe) and connecting through the SWD connectors.
For a general guide, please take a look into the Getting Started for the MCU-Link, installing the firmware and connecting it to MCUXpresso.
For more information about the OpenSDA serial and debug, please look into chapter 2.3 (OpenSDA serial and debug) of the FRDM-KW38's User's Guide, which can be found under "Documentation" in its page (Freedom Development Kit for KW39/38/37 MCUs).
It is also needed to cut the trace at the bottom of the PCB that connects J15 Pin 2 to J12 Pin 4. This will disconnect the SWD_CLK pin to the KW38 so that it will not interfere with the communications to an offboard MCU connected to J15.

If any other doubt comes up, do not hesitate to ask. I hope you find this helpful!
Best regards, Julián