Hi,
The MSP430 support in VisualGDB is implemented via an open-source tool called msp430-gdbproxy. Although it currently only supports erasing the entire FLASH memory, you can easily modify it to erase a custom range instead.
You would need to clone the msp430-gdbproxy repository and edit the MSP430Target.cpp file to support an additional command (e.g. “erase_range”). Then you can remove the original “erase” command from the <sysgcc>\msp430\msp430-bsp\debuggers\core\edp.xml file and add a custom “erase_range” command to VisualGDB Project Properties -> Additional GDB Commands.