Tabletop Events offers a cancellation feature that will allow you to mark a convention cancelled, walk you through the steps to export your data, cancel events, and ultimately refund all your purchases as you wish.
The page has detailed instructions about what will happen in each step. You can choose to do some or all of the steps, based on how you wish to handle your convention's cancellation.
To access it, go to “Convention Tools” > “Convention Setup” and click the “Cancel” item in the navigation bar.
For each cancellation step, you'll be able to see the details for what is included in that step. Please read through the information carefully before you proceed with each step in the cancellation process.
Please note that you must have refund coverage on the account used for convention payout before you will be able to proceed with Step 5.