Put a sign on your studio door explaining the closure and directing people to your website, along with your mobile contact.
Do a big final clean, including under the furniture to get all crumbs and food items - so that you don't get pests.
Take all the rubbish out.
If you have a commercial waste service, schedule a suspension of services after your next pick up.
Turn off all powerpoints in the studio.
If you have a studio landline, set a new answering machine message, or get your phone company to forward calls to your mobile.
Update the front page of your studio website with a notification of how things are impacted by Covid-19. Are you still accepting new enrolments? In what form?
If you have a canteen at the studio, take out all the items that will expire soon and either bring them home or donate them to a charity that provides food for those in need.
Take the toilet paper home, (it's yours now!) but leave at least one week's worth for when you start back up again.
Think through what services will be of no use to you whilst you're closed, and whether or not they can be put on hold for a few months, or relief negotiated. EFTPOS facilities? Internet? Equipment leases? Music licensing?
Clearly communicate with your staff about when you will need to stop paying them, and help them get the support available to them from the government.
Look at what classes weren't profitable BC, and consider how you might be able to consolidate some of your timetable AC - with the assumption that when things go back to normal, your numbers might have taken a bit of a kick.