Clone an ESXi VM in 10 easy steps
1. Access VmWare vSphere Client.
2. Make sure the machine to be copied is powered off.
3. Go to the Configuration tab and click on Storage in the Hardware menu.
4. Right click on the datastore holding the machine to be copied and browse to the machine.
5. Select the vmx and vmdk files (should be the two files at the top of the list), right click and select copy.
6. Browse to the datastore where you want the new clone to exist, create a new folder named for the machine.
7. Open the new folder and right click paste the two files. this will take some time depending on the sizes.
8. right-click on the pasted vmx file and select “add to inventory”, enter a new name for the new machine.
9. Close out of the datastore windows and access the Virtual Machines tab. The new machine should be listed.
10. Power on, open the console, and select “I copied it”
Boot it up and make sure you have your desired network settings. Might need to refer here for that.
Source of this information, excellent instructional video i found here