It depends how you measure it. The Chuquicamata opencast copper mine in Chile has the greatest volume of excavated earth (roughly 9 billion cubic metres) but it’s a ditch rather than a hole.
Bingham canyon, in Utah, is the deepest at 1.2km but it was a canyon to begin with so not all of it is man-made.
The Mir diamond mine in Siberia is the deepest ‘proper’ man-made hole. It’s 525m deep and 1,200m across. There’s a no-fly zone above it because the downdraft created by the hole had caused several helicopters to crash.