WASHINGTON — President Barack Obama has quietly slowed deportations by nearly 20 percent while delaying plans to act on his own to potentially shield millions of immigrants from expulsion. The Homeland Security Department is on pace to remove the fewest number of immigrants since 2007, according to an analysis of its data by The Associated Press. Immigration and Customs Enforcement, the federal agency responsible for deportations, sent home 258,608 immigrants between the start of the budget year Oct. 1 and …