That’s a good point, it’s not there, but I know from the CC3000 patcher that it’s possible. Let me look into it
[Edit] Ask and ye shall receive. Call the below function anytime and it will reset into DFU mode
void DFUMode()
{
// From https://github.com/spark/cc3000-patch-programmer/blob/master/src/main.cpp
//RESET INTO DFU MODE PLEASE!
FLASH_OTA_Update_SysFlag = 0xFFFF;
Save_SystemFlags();
//THE BACKUP REGISTERS, THEY DO NOTHING!!
//firmware state flag
BKP_WriteBackupRegister(BKP_DR10, 0xFFFF);
//system health -- SET_SYS_HEALTH(0xFFFF);
BKP_WriteBackupRegister(BKP_DR1, 0xFFFF);
//OTA_FLASHED_Status_SysFlag
USB_Cable_Config(DISABLE);
NVIC_SystemReset();
}