How can i clear the useless items on the ground quickly in a singleplayer game? Any commands can use?

ok, thanks. these suggestions are useful

There is no command for that

In singleplayer game advance settings, look for "Despawn_Dropped_Time"
The numeric value there is the amount of time in seconds before your dropped item disappears. Setting it to 20 would mean that when you drop the item, it will disappear after 20 seconds or so.