Let's remove them...
1. Open PSE and a picture you want to work with.
2. Click on the clone tool (its the one that looks like a rubber stamp). Hit the "option" button (the alt key if you are not a mac user) and click an area near your mistake that is close to what you want to paint over your mistake with (did that make sense?). You are basically copying an area and will repaint over your mistake with this. At first, set your opacity to 100%.
3. Once they are gone, you may want to adjust a bit. Sometimes it looks a little obvious where you have done some altering. Change your opacity to a lower number (somewhere between 25% and 45 % seems to work well for me) and paint over the area a little bit more. It should help it to blend in much better.
Can you believe how easy that was?