Create a new mission, create the following init.sqf and preview the mission. Then kill the unit spawned by the script, and notice how the dead body is not deleted.
sleep 1;
_unit = group player createUnit ["B_Soldier_F", getPos player, [], 0, "NONE"];
waitUntil { !alive _unit };
sleep 1;
deleteVehicle _unit;
hint "Dead unit deleted. (NOT)";