Hi,
Hope you are doing well. With the demo example, the reader will see the NDEF message "Test". Then, if you write a new NDEF message, you will see this new NDEF, until you reboot the board.
But, if you don't want to write NDEF's, could you please check the section 6.7 of this Application Note? (NXP-NCI MCUXpresso example).
Hope this helps.
Best Regards,
Ricardo