To turn off the "Format as Table" feature in Excel 2007, follow these steps:

1. Click anywhere inside the table that you want to turn off the formatting for.
2. Go to the "Design" tab in the ribbon at the top of the screen.
3. In the "Table Styles" group, click on the "More" drop-down arrow in the bottom right corner.
4. Select "Clear" from the drop-down menu.
5. A pop-up window will appear asking if you want to convert the table to a normal range. Click "Yes" to confirm.
6. The table formatting will be removed, and you can now merge cells as needed.

Note that turning off the "Format as Table" feature will remove all of the table formatting, including any conditional formatting or formulas that were applied to the table. If you want to keep these features, you may need to manually copy and paste them into a new range of cells before merging.