Edgerouter Lost Password : r/Ubiquiti (reddit.com)

Boot EdgeRouter into single-user mode or boot alternative image | Ubiquiti Community

Connect-up to the serial interface and reboot the device. During the early boot process press the Esc key repeatedly until you see the u-boot prompt (there may be a more elegant way to do this, but this approach is effective), which will look something like Octeon ubnt_e300(ram)# (note that the e300 is model specific). 

printenv

note: all commands required a space at end of line

Note the semicolon; this breaks the boot process down into two stages, first is loading the kernel, and the next is actually booting the system. The second command contains the kernel command line, which will require modification before we boot.

fatload usb 0 $(loadaddr) vmlinux.64 

Then enter the bootoctlinux command but append single init=/bin/bash to the end of the line

cat /config/config.boot ( version 1.0.1 ) to find settings or vi to edit password in plaintext.