How do I reset the BIOS password?

Lenovos do not have a backdoor password, and the password is stored in NVRAM, not the CMOS RAM as a lot of laptops on the consumer side did for years. You need to reflash these with a clean BIOS (read on for more info) to clean them up.

On the business models (ThinkPad) with older models like the XX30, the solution was to find the ATMEL chip and short 2 lines, or use an HW tool to do it (sold by an Australian); even this no longer works on the newer Think laptops (XX40-present), with the POP being in the protected NVRAM as well now. It's a motherboard replacement for both the consumer and business system unless you can get Lenovo to reflash both the BIOS and EC firmware, as well as reset the encrypted password data if it's separate (yep, both need to be reflashed) for a fee or get the reference Lenovo BIOS and EC firmware (as well as your S/N, UUID if needed, and machine type), dump the locked BIOS and EC firmware as a backup AND THEN flash the clean BIOS and EC firmware, then in reprogram those 3 critical pieces of data.

Regardless of the type, the newer laptops (Haswell-present) either use Intel Boot Guard or VERY ROBUST signature checks, which means any attack on the NVRAM or BIOS code if you dump it to attempt to reset it and remove the password or attacks on the ATMEL chip corrupts it and kills the boot process until the "correct" BIOS image is in place which will make the password issue come back :(. These new Lenovos (IdeaPad and ThinkPad) are not built around the idea of security theater like the old ones anyone who knew how to locate the ATMEL chip or properly dump and hack the BIOS can fix now.
HP has some real security in place since the process can only be done on the right machines (read: older and exploited, takes a few years to be added to the list of ones which can be cracked) by dumping the BIOS (chip desoldering often needed with HP as they use a BGA part in newer models because it's physically more secure unless you can get enough of a bite with a clip which can read it), the unlocking tool (easily found online, NOT NAMING NAMES!), and reflashing the original "unlocked" BIOS to the main EEPROM (which will get shadow copied to the backup). Main swapping is not possible as you CANNOT MIX THE MAIN AND BACKUP BIOS on those laptops unless you have both ROMs from a clean board (at which point.... swap the board unless it has LD but a "clean BIOS"). Dell is the only vendor left who practices BIOS security theater (please keep practicing it, Dell. It helps the used market and doesn't turn them into parts machines).