Flashing ROM on a used Samsung Note 4 I have a used note 4 and want to make sure there is no spyware or malware on it. I know some can survive a factory reset. Somebody told me to flash a rom and recovery image but not how to do this. I searched and came across a video of a person using a program called odin to do this, however after he was finished all his apps were still there. If this completely cleans the phone why are his apps still there? 

What would be the best way for me to actually wipe everything on the phone?
It's better to link the video so we know what you are exactly talking about.
My guess is you watched a video about rooting using ODIN. Yes, that won't wipe your device clean. However you can also use ODIN to flash entire firmware which cleans up everything on your device. 


Here's a guide to use ODIN to flash stock firmware.