Organisations are not deleted from the Unicorn LMS so they can be easily restored if required.
Navigate to the Menu and click on Organisation and Users.
Click on the Show drop-down menu and choose Archived.
Click on the organisation's name.
Click on the Details tab on the left-hand side.
Click on Restore.
Click on Yes in the pop-up window.
The organisation will be restored, along with its users' accounts.