Delete chunks using Chunk Explosives. Good for resetting old ore patches etc as well as forcing chunk re-generation for whatever reason. On multiplayer worlds it is only usable by admins. (Not tested thoroughly on MP).

Can be used to get rid of industrial amounts of garbage.

To delete a chunk, place the Chunk Explosive chest on the relevant chunk.
To abort deletion, mine the chest before the timer is up.

To change the default 5 second timer, use the relevant mod setting.