erase the entire flash memory inside the main() function ???

in my h/w, i cannot control boot0 pin to high level for dfuse demo program.

however, i find that

When the entire flash memory is erased, st32L4 chip automatically goes to enter usb dfu mode.

hence,

i want to know how to erase the entire flash memory inside the main() function.

please let me know it is possible or not

thanks a lot