one way might be to copy all the VM files from your datastore (via. scp / you need to enable ssh first on your esxi).
Ask your ISP if you can deliver them the VM as an OVF. That's in my opinion the smoother way of doing it. Mark your VM in the vSphere client, go to file-> export -> export OVF Template
and your VM will be exported in a standardized format. This is a format your ISP should be able to import.