Create a new admin on an ESXi box

Select the ESXi host in the vSphere client and select the Users tab when in Inventory workspace

Right click on the user area and select Add...

Enter a new login name, user name and password then click OK

To make the new user an administrator right click on the ESXi host in the navigation pane and select Add Permission...

Click Add and select the new user you added then click OK

In the Assigned Role select Administrator then click OK