Yes, there is a way to kick someone out of a spreadsheet if they have left it open on their computer overnight. Here are the steps you can follow:

1. Open the shared workbook in Excel.
2. Click on the "Review" tab in the ribbon.
3. Click on the "Share Workbook" button in the "Changes" group.
4. In the "Share Workbook" dialog box, click on the "Advanced" tab.
5. Under the "Who has this workbook open now" section, select the user you want to kick out.
6. Click on the "Remove User" button.
7. Click "OK" to confirm the action.

This will remove the selected user from the shared workbook and they will no longer be able to make changes to it. However, it's important to note that this will not close the workbook on their computer. They will need to manually close the workbook to ensure that they are fully removed from it.