ESXi is NOT Linux. Do not try to secure it like Linux. Sudo does not exist on ESXi. When you login to ESXi you are placed within a busybox process. Normal rules do not apply. No one should be logging directly into ESXi unless it is a break glass situation.
Please refer to the security configuraiton guide to determine the best remediation for ESXi based on your profile.
Now if this is about one of the management appliances, let me know.
Edward L. Haletky, aka Texiwill