Restore factory settings ASA5505 aka reset

Connect console cable.

Switch off the device.

While turning it on, press ESC to access ROMMON.

Execute command to skip startup-condif

confreg 0x41
boot

booting

Once loaded, elevate privileges and return register

enable
configure terminal
congigure factory-defaults

config-register 0x01
write memory

reboot

reload

Next boot