Legally required doesn’t really mean much evidently.
Check it out:

Nearly 900,000 illegal aliens who have received a final order of removal are still in the United States – and about 167,000 of these are convicted criminals who were released by ICE and are currently at large, a new analysis of government data by the Center for Immigration Studies (CIS) shows.

According to the CIS’s review,of a leaked Dept. of Homeland Security (DHS) document, 883,000 total illegal aliens are legally required to leave the U.S, but are still here: