Can I upgrade ESX 5.5 to 6 from the host? From vCenter?

OR must I be at the console?

I have a 5.5 host that lives in a vCenter right now.  I need it to be in my new vCenter 6 that I spun up.  After some work, I have decided to offload the VMs to the new vCenter and then upgrade the 5.5 host and then bring it into my new vCenter and the load balance the VMs between the new host and the newly upgraded host.

Can I upgrade the 5.5 host from vCenter or must I walk up to the host with a USB stick?

I do not have ILO or iDRAQ access to the host.  I do have vSphere client access and vCenter access.

I just need some direction to where I can read about how to do the upgrade.

Thanks

cliff