Let's say we drew a 3D rectangle and we accidentally made a mistake by drawing another rectangle that intersects it:

To fix this, select the erasing tool from the tool palettes OR type “_erase”:

Next we select the object(s) we want to erase by clicking on them:

Then we press the ENTER or RETURN key, which ever one you have on your keyboard.

Problem solved - There is also another simpler way to do this. Simply click on the object you want to delete:

And press the DELETE key on your keyboard! You may think this is simple, but it took me 30 minutes to figure out how to erase when I first started AutoCAD so this is why I decided to make a tutorial on it.