Use the interactive installation option for small deployments of fewer than five hosts.
In a typical interactive installation, you boot the ESXi installer and respond to the installer prompts to install ESXi to the local host disk. The installer reformats and partitions the target disk and installs the ESXi boot image. If you have not installed ESXi on the target disk before, all data on the drive is overwritten, including hardware vendor partitions, operating system partitions, and associated data.
If you are installing ESXi on a disk that contains a previous installation of ESXi or ESX, or a VMFS datastore, the installer provides you with options for upgrading. See the vSphere Upgrade documentation.