Instead of using the CTRL key and the left mouse button to deselect data, you can use the mouse without using the keyboard.
This deselect method works with following tools: Line, Circle, Rectangle, Paint Brush, and Lasso.
To Deselect with only the mouse:
Pick the selected area on the model using the left mouse button.
Then (with the left mouse button still held down) press and hold the right mouse button during the selection.
Clicking the right mouse button will act as the deselect.
This will also work using the middle mouse button.