I have the Merlin 3004.388.8_4 firmware on my ASUS RT-AX86U Pro router. I would like to revert back to the stock ASUS firmware. Can someone please help me how to do this?
Just manually flash the Asus stock firmware as you normally would through the router GUI. It is sometimes recommended to do a hard factory reset after flashing from Asus stock to Merlin or Merlin back to stock Asus.
You may want to record your settings before performing the firmware flash and then manually reconfigure the router after performing a hard factory reset.