Edit VM User Template from Sunstone

Is there a way to edit the User Template of a VM from Sunstone?

I was looking to add the HOT_RESIZE attribute and could only do it via POSTGRES which may not be the safest and easiest way. Or is there any alternative mechanism that is recommended?

You can always use the Advanced mode instead of the Wizard mode in OpenNebula Virtual Machine Templates — OpenNebula 6.4.2 documentation