As your post needs moving to the area for ESXi, I have reported it to the volunteer moderators.

To answer your question: https://kb.vmware.com/s/article/1317898

Check out this thread.

https://communities.vmware.com/t5/New-Security-Advisory-VMSA-2021/Forgot

If its managed by a vCenter:

1. let the ESXi join the Windows AD too and you can log into ESXi with AD credentials and change password
2. With the help of a Host Profile you can set a new ESXi root password as well (needs Enterprise Plus)

or when its a ESXi 6.7

1. Booting with a Linux LiveCD or the gpartedISO and extract bootbank TGZ and mount it. You can that use "passwd" to write into the etc/shadow. Done that a dozen of time in the last years. It took 15min.

Regards,
Joerg

Check this blog:

4 ways to reset root password

https://www.vmwareblog.org/forgot-esxi-root-password-no-problems-4-ways-reset/

In case this is a standalone host - reinstall ESXi but preserve your VMFS datastore. VMs will stay with you.