Did Brigham Young teach that Adam was God the Father?

The short answer

Yes. The 1852 sermon calls Adam “our Father and our God.” Brigham Young repeated the teaching in 1873 and said God had revealed it to him. Church President Spencer W. Kimball denounced the theory in 1976. In current Latter-day Saint scripture, Adam is Michael, and God speaks to Adam about Jesus as His Only Begotten Son.

What did Young say?

In 1852, Brigham Young called Adam “our Father and our God, and the only God with whom we have to do.” The published sermon identifies him as Michael and as the father of Jesus. Young repeated the teaching in 1873 and said God had revealed it to him. 1852 sermon, pp. 50–51 · 1873 newspaper report

What does the Church teach now?

D&C 27:11 and 107:53–55 identify Adam as Michael, the archangel and ancient of days. Moses 6:51–52 distinguishes God from Adam as God speaks to Adam about His Only Begotten, Jesus Christ. In 1976, President Spencer W. Kimball named the “Adam-God theory” and said, “We denounce that theory” as false doctrine. Moses 6 · D&C 27 · D&C 107 · Kimball, 1976

A reply you can use

“Young taught Adam–God and said it came by revelation. I think he was wrong here. In Moses 6, God addresses Adam and speaks to him about His Son. That gives me a scriptural reason to agree with Kimball’s rejection. I take the disagreement seriously when weighing other prophetic claims.”