On the UART VCOM interface (115kBaud) there are menus that allow you to read, write, erase flash, plus a parameter system.
https://github.com/uTasker/uTasker-Kinetis contains complete applications with parameter and file systems in Flash and API according to https://www.utasker.com/docs/uTasker/uTaskerFileSystem_3.PDF
It also allows the Flash operations to be emulated by running the project in Visual Studio for easier learning and development.
[uTasker project developer for Kinetis and i.MX RT]
Contact me by personal message or on the uTasker web site to discuss professional training, solutions to problems or rapid product development requirements
For professionals searching for faster, problem-free Kinetis and i.MX RT 10xx developments the uTasker project holds the key: https://www.utasker.com/iMX/RT1064.html