Deleting a part of a file

I know there's no direct method of deleting a part inside a file. Maybe someone know the best/fastest method to do this ? I'm thinking of:
1) write data to new file (and just omit what i want to delete)
2) move data within a file without creating new one

Any other ideas ?

Whatever way you choose, you'll have to rewrite all data that is after the block you wish to remove. So solution 2 is better than 1.