Yes there is. You must record a macro. If you know how to record one,
great! but just in case I'll describe as best I can.

During the macro recording process, you CAN NOT use your mouse. It
will record only keystrokes.

Make sure you have selected the first cell to be edited. (Don't double
click it, just select it)
Go to Tools - Macro - Record New Macro
Assign a keyboard shortcut for it.
Then you will see the little window with a button to press to stop the
macro recording process on your worksheet.
Press F2 and that will allow you to edit the cell
Then press your arrow keys to move your insert point to "-"
Delete the "-"
Press enter
Press the stop button on the macro window.

You will have to record two seperate macros since you have two
different formats for your cells.

Then you just press ctrl+ whatever shortcut key you selected, and it
will perform that action to every cell you ask it to.