You will be asked by the moderator to show around by rotating your laptop. You should not have papers writings etc around you. You should be alone. If you can have this environment along with system compatibility, you can take the test from office. I took test from home itself as I was not sure if my office network can block screen share etc. Moderator asked me to remove tablecloth from my desk . I guess a clean, uncluttered meeting room in after hours should be fine to take the test from office. If you are confident that you don’t have any network/software restrictions on your office laptop.
Also, If it you don’t want this to be a secret in office , just talk to your IT and your manager. They may help you.