You will need to Contact HP to request a "Regionalization Reset". There should not be any charge for this, it is covered as part of the cartridge warranty. You will need to have access to your computer and printer while on the line with HP. You will also need to have a set of cartridges for the new region, once the reset is complete cartridges from the original region will no longer work. HP's web page on the subject is here.
I have also seen folks having success requesting the regionalization reset through HP's Facebook Support Page here. You may need to wait until tomorrow morning, they are generally open during US business hours.