A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
On that worksheet, click in a cell and then press Ctrl + End. That will take you to what Excel thinks is the last cell of data.
If we assume your data in cells A1 to T20, click in cell U1 and then press Ctrl+Shift+Right arrow. Keeping Ctrl+Shift held, right click one of the selected cells and choose Delete and Entire Column. That takes care of extra columns.
Now click in cell A21, press Ctrl+Shift+Down arrow. Keeping Ctrl+Shift held, right click one of the selected cells and choose Delete and Entire Row. That takes care of extra rows.
Save, and it should work now.