In order to reset the password from the boot menu you need to interrupt the boot process of the switch. Console in and power cycle the switch, you should see the Cisco logo, then you have about two seconds to hit a key to get the boot menu. If you miss it (or it times out once your in it) just power cycle the switch again to bring it up again. On the switch in front of me it is option 3 to reset the password.
However it is possible to disabled this option, so if it is not available even in the boot menu the only way to regain access to the switch will be to factory default it by holding down the rest button for 30 seconds. You will then have to reconfigure the device, but the default login of cisco/cisco will get you in once the switch resets.
