In order to stop the deletion of cells in Excel, there are a few things you can do. First, you can protect your worksheet by going to the Review tab and clicking on Protect Sheet. This will prompt you to enter a password, which will prevent anyone from making changes to your worksheet. You can also add data validation to your cells, which will prevent users from entering invalid data. Finally, you can hide your cells by going to the Format tab and selecting Hide & Unhide > Hide Columns or Hide Rows. This will make it so that users cannot see or delete your cells.