Eraser in Illustrator

[Миракбаров5FF2]

 I have used an eraser and then the place where removed objects were initially located becomes like this (see picture) and it remains the same when I save it (e.g. as pdf). I think that reason is that I am using an eraser to remove elements of the traced picture. Yet I do not know how to avoid this problem and I really need help.

[Ton Frederiks]

Select only what you want to erase or lock what you dont want to erase.

You erased the background, which has a light grey stroke.