Open a new flash document and change the document size to 250 X 100 and choose a background color of your choice.
Click on the Text tool and type out some text on the stage. Select the Freeform Transition tool and size it to fit the stage.
Next we will need to break the text apart. Select the text with the selection tool the click Ctrl B twice. The first break will break each letter apart and the second break will then break apart the letters.
Now we will start creating our animation. The first frame will be the whole text so we don't need to do anything in frame 1.
Press F6 and a keyframe will appear in frame 2 without going to the Timeline. Choose the eraser tool and erase the end part of the word. Remember that we are erasing backward so you want to think about how you would actually write the word then erase in reverse. If you hit the refresh button on this page you will see that I didn't use the correct sequence for the letter F. Instead of correcting it I decided to leave it to show you what would happen when you did not erase in reverse order:
Continue clicking F6 and erasing small parts of the letters until you have all the text erased. Between each letter include two frames to it will give the appearance of picking up the pen and moving it to the next letter:
Now we need to reverse the order of the animation. Select all the frames by holding down the left mouse and dragging through all the frames:
Right click on the selected frames and select Reverse Frames.
Click in the last frame of your animation and click the add layer icon on the Timeline to add a new layer:
Name this layer Actions. Click in the last frame of your actions layer and click F6 to insert a keyframe.
Click F9 to open the Actions panel.
Click Esc ST to put a stop action on this frame. Escape ST is the shortcut for the stop action command.
and type out some text on the stage. Select the Freeform Transition tool 
and size it to fit the stage.
the click Ctrl B twice. The first break will break each letter apart and the second break will then break apart the letters.
and erase the end part of the word. Remember that we are erasing backward so you want to think about how you would actually write the word then erase in reverse. If you hit the refresh button on this page you will see that I didn't use the correct sequence for the letter F. Instead of correcting it I decided to leave it to show you what would happen when you did not erase in reverse order:
