To reset the settings on the Allied Telesis AT-8000S switch, it is enough to connect to it via SSH or an ordinary console null-modem RS-232 cable at a speed of 115200.
By default, login is manager, password is friend.
And delete the file “startup-config” in which the entire configuration is saved:
delete startup-config
After that reboot the switch:
reload y y
See also my articles:
Configuring Allied Telesis AT-8000S
Allied Telesis AT-8000S Firmware Update