Open your Cubase project and select the "Split" button. It appears at the top of your screen, indicated by a black pair of scissors. Using this button, you can divide your audio regions at any point with the click of a button.
Hover your mouse over the region (beat) that you want to cut. The region will appear as a horizontal bar, containing a series of wavy lines, or sound waves, on your main project window. Click your mouse over the beginning of the quarter note that you want to remove. To find the beginning of the note, just follow the time line along the top of your window, which looks like a ruler. Each small vertical line on the ruler represents a quarter note. For instance, if your song uses a standard 4/4 time signature, you will see four vertical lines between each number. For a 3/4 time signature, you will see three lines between each number.
Click your mouse over your recorded region again, this time beneath the next quarter note on the time line. For example, if you originally clicked the first vertical line corresponding to a number, then you would now click the very next line on the ruler. You now have a separate, divided region, the length of one quarter note.
Click the arrow button at the top of your project window, near the "Split" button that you selected before. Click the center of your quarter note to highlight it, and then click "Delete" on your keyboard to remove it. You can now use your mouse to rearrange your remaining regions, drag them together or make further changes.