How do u kill maple seedlings

You pull them out one by one !

Where are they, if in your lawn just keep mowing them down.They will finally give up

In garden areas, if you get them while they are still tiny, they are easy to get out with a hoe, but once they have two real leaves, their roots are really in the ground and it isn't even easy to yank them out, so just chop at them.

Dig them up, with all roots..