I'm about to update firm ware and am wondering if I should delete the existing FW from the Micro SD before installing new Firm Ware.

Yes. You should only have one BIN file in the root of the memory card.

Once your firmware is updated, the file on your SD card has done its job and you can delete it.

Labroides Posted at 2017-2-26 06:21
Once your firmware is updated, the file on your SD card has done its job and you can delete it.

What I am trying to say is, should I format the SD Card before installing the new firmware or does the old FW need to be on the SD for the update?

I answered your question above. You should only have the BIN that you want to install in the root of the memory card.

Thanks Captain!!