The blue symbol in the bottom right corner of a cell is called the fill handle. It is used to quickly fill a series of cells with a pattern or sequence. When you click and drag the fill handle, Excel will automatically fill in the adjacent cells with the pattern or sequence that it detects.

In your case, it sounds like the fill handle has been used to fill in a pattern or sequence across multiple pages of your worksheet. If you delete the cell or column that contains the fill handle, Excel will automatically move it to the next available cell or column.

To delete all the additional pages in your worksheet, you can try the following steps:

1. Click on the sheet tab at the bottom of the Excel window to select the sheet that you want to delete.
2. Right-click on the sheet tab and select "Delete" from the context menu.
3. In the Delete dialog box, select "Delete entire sheet" and click OK.
4. Repeat steps 1-3 for each additional sheet that you want to delete.

If your worksheet is linked to another document, you may need to update the links after deleting the sheets. To do this, go to the Data tab and click on "Edit Links" in the Connections group. In the Edit Links dialog box, select the link that you want to update and click "Update Now".