Yes. To edit what is already on the note: tap the three dots in the upper right hand corner to allow you to replace strokes with a different pen tip, color, width, or opacity. Select new pen type, touch the lines you wish to change, and hit the preview eye. To cancel (X) or accept (check mark).
To add/erase lines: press the pen icon in the bottom middle of the note to get into edit mode. A set of different writing instruments allows you to choose the effect. Touching one of the writing instruments will allow you to set the width and transparency of the writing. Touching the black dot at the bottom left opens up a color wheel that allows writing in different colors. On the upper bar an eraser icon allows your finger to remove ink from the note.
Writing and drawing on the app can be done with your finger or a tablet stylus. You can also edit in real time with your RoWrite tablet. Anytime you enter into edit mode and write on the tablet your pen strokes will appear on the note in the form of the writing utensil, width, and transparency that is selected on the app. The exception is the eraser which can be used only with finger or stylus directly within the app.