What to do about cement & metal supports left after deck removal?

[Suzanne Player]

When you have a deck removed (or made much smaller), what do you about the old metal & cement supports?  Are they a safety hazard if left in?  Does covering with new soil & re-seeding the area work or would they be in issue if the ground changes over time (due to rain)?

What type of contractor would you call to remove them completely?