Of course it has not been removed from the National Curriculum.

According to BBC "Some schools avoid teaching the Holocaust and other controversial history subjects as they do not want to cause offence, research has claimed.
Teachers fear meeting anti-Semitic sentiment, particularly from Muslim pupils, the government-funded study by the Historical Association said.

"Some schools" in the context of a nationwide report could be "many" or "a few". Figures are not given.
So this is factually correct:
Many UK schools removed The Holocaust from their school curriculum because it "offended" members of the Muslim population who claim it never occurred.