No one is "erasing" any history. The Civil War should be taught in history classes, shown in museums and documentaries, etc.
But a state or local government putting up a statue implies some kind of place of honor, and the Confederacy, which was formed 100% to preserve slavery and was responsible for the deaths of hundreds of thousands of Americans, should not be honored with any public statues.
Imagine if there were an unsuccessful Communist rebellion within the US that took years to put down and killed half a million soldiers. Would it be appropriate for cities to put up statues and monuments to honor these Communists? Didn't think so.
So . . . a "Civil War" statue is essentially an "honor" to the confederacy which supported keeping slavery in place . . . which makes all "Civil War" statues offensive. Certainly, I agree that slavery is highly offensive, so your explanation makes sense to me.
Follow-up question: do you think ALL "Civil War" statues should be removed, regardless of their location and regardless of the majority opinion of the local citizens?
For example, if the vast majority of the citizens of Podunk, Floribama want to KEEP the "Civil War" statue at the courthouse square, then should they be permitted to keep the statue? Or, should the statue be removed regardless? Should physical force be used to remove the statue, if necessary?