If you want to perform a password recovery you have to do the usb boot method. To do this you need the image of the firmware save it on a usb. Connect the usb on the router and power cycle. Then use the break sequence. (For me control+ c always work) and from the menu select the usb and boot it. This will install the ios image tha you have in the usb. And the router will boot up factory default. So you will lost any configuration the router had.
If you can access the cli with a user with admin permission you can use commit replace command from the config terminal. This will erase all the configuration and boot up as factory default. Do this from console and not from remote access cause you will lose connectivity.
You can find the documentation for the password recovery under NCS 540 Disaster Recovery
