To select cells from any cell to the last cell in the sheet's used range:
The keyboard shortcuts Ctrl+Shift+End and Ctrl+Shift+Home enable the quick selection of cells either down to the last cell of the sheet's Used Range or to the first cell (A1), respectively.
Example:
To clear the cell content from cell A7 to the last cell in the sheet's Used Range (cell G13 in this example):
1. Select cell A7.
2. Press Ctrl+Shift+End.
3. Press Delete.
Screenshot // Selecting Cells from Any Cell to the Last Cell in the Sheet's Used Range