In the state of Utah, Brigham Young is idolized, having his name displayed on many buildings and sites, and even a prominent school has been named after him. Unfortunately, there is undeniable historical evidence that Brigham Young was a staunch defender of racism and slavery, and he intended to make Utah (formerly the State of Deseret) a predominantly white state, built on racist ideals propagated by shameful religious rhetoric.

When he arose to power, he stripped African Americans of their religious priesthood, forbade inter-racial marriage, and cultivated inequality for all people of color. For over 150 years, leaders of the Mormon church opposed civil rights, opposed inter-racial marriage, and opposed racial equality. 

Why then should we, a modern society which believes that "all men are equal," honor and literally idolize a man who fought so vehemently for white supremacy. We need to atone for the sins of the past, clean the slate, and build a better and brighter future. For which, the first steps are admitting our ancestors were wrong, apologizing for their mistakes, and removing their racist influences. Just as we demand that our society remove systemic racism, we demand the statue of Brigham Young be removed from Salt Lake City. 
 
 Quotes from Brigham Young: 

"...inasmuch as we believe in the Bible, inasmuch as we believe in the ordinances of God, in the Priesthood and order and decrees of God, we must believe in slavery"

-A SPEECH GIVEN IN THE JOINT SESSION OF THE LEGISLATURE, JANUARY 23, 1852
 
 "Shall I tell you the law of God in regard to the African race? If the white man who belongs to the chosen seed mixes his blood with the seed of cain, the penalty, under the law of God, is death on the spot. This will always be so."

-LDS PROPHET BRIGHAM YOUNG JOD, VOL. 10, P. 110

"...we must believe in slavery. This colored race have been subjected to severe curses, which they have in their families and their classes and in their various capacities brought upon themselves. And until the curse is removed by Him who placed it upon them, they must suffer under its consequences; I am not authorized to remove it. I am a firm believer in slavery"

-BRIGHAM YOUNG SPEECH GIVEN IN THE JOINT SESSION OF THE LEGISLATURE-JANUARY 23 1852
 
 *All quotes are from missedinsundayschool.com

There are the sources there.