Of course, you can. You can select a cell with your formula, enter the Edit mode, and then type or delete the $ sign manually. Or, select the reference you want to change and press F4 on your keyboard to toggle between 4 reference types. And then, you repeat the above steps for every single cell.
With the Convert Formulas tool, you simply select a range of cells and click just one button on the ribbon to change all references in all formulas.