The question of these Confederate monuments is, in my opinion, a bit more complicated than "they're trying to tear down history." Confederate monuments on battlefields, in and outside of museums, in historical locations, etc. are one thing and I believe those should absolutely be protected.
However, when you examine the historiography of many Confederate monuments and memorials, they have little if anything to do with the Civil War and history. Far too often they are nothing more than testaments to white supremacy and were placed after the failure of Reconstruction to commemorate the southern redemption of forcing African-Americans to the status of second rate citizens.
The vast majority of these monuments, on public grounds no less, were put up during the "nadir of race relations" and they actually celebrate the ascendancy of Jim Crow, segregation, and the effective muzzling of the 14th and 15th Amendments.
Primarily through the actions of organizations like the Daughters of the Confederacy, who worked closely with the Ku Klux Klan, the landscape was cluttered with monuments and memorials that celebrated the Lost Cause and actually misrepresent history.
See for instance the Montana Confederate Memorial, which was recently taken down, it was a completely misleading monument since there were no Montana Confederates. Montana did not even become a state until 1889 some 24 years after the Civil War ended.
https://en.wikipedia.org/wiki/Confederate_Memorial_Fountain_(Helena,_Montana)
If you looks at the landscape in Maryland there's a plethora of Confederate monuments. There are three times as many Confederate monuments as there are Union monuments in Maryland. Looking at the monuments you would think Maryland was a Confederate state. But Maryland remained loyal to the Union and sent three times as many men to fight for Union as they did to the Confederacy
The fact of the matter is, the Confederate States of America was formed for the express purpose of protecting the institution of slavery and to insure the continued enslavement of four million African-Americans. That fact must be recognized when examining monuments and memorials on public lands and buildings.
For instance, the Battle of Liberty Place monument that was recently removed in New Orleans was simply disgusting. It had nothing to do with the history of the Civil War, but instead celebrated members of the Crescent City White League attacking the mixed-race forces of the state government in an attempt to re-institute white supremacy in Louisiana in 1874 (and actually had language celebrating white supremacy in the engraving on the monument that was added in 1932).
Why isn't Confederate Lieutenant General James Longstreet chiseled into Stone Mountain, Georgia rather than two Virginians and a Mississippian? Longstreet won the greatest Confederate victory in the west in Georgia at Chickamauga. Longstreet was a Confederate hero, Robert E. Lee’s second-in-command, and actually a Georgian for most of his life. Why does he have so few statues (Longstreet has two statues, one at the site of his home in Gainesville, Georgia and one at the Gettysburg battlefield) when Lee, Jackson, Forrest, etc. have dozens?
Well, the answer is obvious, Longstreet supported civil rights for black people after the war and led those mixed race forces against the white supremacists at the Battle of Liberty Place, as such he was a "race traitor" as far as the South was concerned.
Longstreet sought to heal the wounds of the Civil War through his actions, something that Lee is often given undue credit for, but that Longstreet actually did. Lee is lauded for his supposed attempts at reconciliation, while Longstreet was vilified for his. What is the difference? Lee stayed loyal to white supremacy and opposed civil rights for black people until the day he died, even going so far as to testify to Congress in opposition to black voting rights.
If the monuments were truly about bravery and battlefield courage Longstreet would have as many statues as Lee, Jackson and the others. But it is not about battlefield courage and honor, it is about white supremacy.
Most of these monuments in public spaces are merely misleading "Lost Cause" memorials that do not explain history, but rather muddy it and mislead people. They were put up to celebrate the return of white supremacy to the post-Reconstruction South. They were intended to make a statement to black people that the old South had returned and they better watch out!
Monuments are not history. Monuments are “commemoration”, meaning what we chose to celebrate or memorialize. At one time this nation publicly celebrated white supremacy. Do we wish to continue such celebration?
We can never solve the problem of racism as long as we commemorate and celebrate the memory of those who fought a war to preserve negro chattel slavery. Battlefields, cemeteries, and museums are the proper places for Confederate statues, flags, and icons. Not public squares, parks, and courthouses.
I do not take the removal of historical monuments lightly, but, as I stated, it is far more complicated than "leave the monuments alone."