How to hide VMs

Hide VMs with sensitive information so other people who aren’t familiar with this technology can’t see theses VMs. It’s more secure than not to hide and it’s faster than restore from backup.
I think Qubes OS distinguishes VMs by some folders, so how about moving them to other places so Qubes OS can’t distinguish them anymore?

You need to be more specific. What do you mean by “this technology”, do you mean Qubes itself? How exactly do you want to hide the VM?

And what do you want to hide? Full disk encryption should solve most of your problems unless someone else also uses this Qubes system. For hiding a single VM you can probably also store them locally in encrypted form.

“this technology”, about hiding VMs. I assume other people that may contact my computer can only click and click.

I’m afraid other people such as airport security may check my computer, because the probability is not big so I don’t want to backup and restore every time.

How to do this?

So, you assume they’re dilettantes or don’t have much time to bother with you and hiding is enough? Well, I’d take my chances only if not carrying with me something sensitive or dangerous. But then, what would be the point of hiding it?

See these: Encryption of app vms?, Setting Up Per-qube Encryption and The last link is only available to users with Trust Level 2 (“Member”) and above.

Store them on a an encrypted volume? Or encrypted external media?
Depending on your use case you can maybe just encrypt the data and not the whole VM.
If someone is going to take a closer look at the device or OS (and is specifically looking after you) then they could possibly bug your PC. A standard Qubes install with FDE might not be enough in this case.

Take a look at: Feature Request: Peace of mind when crossing borders - #9 by Sven