Put in your .emacs file.
(setq make-backup-files nil) ; stop creating ~ files
What the variable does...
make-backup-files is a variable defined in `files.el'.
Non-nil means make a backup of a file the first time it is saved. This can be done by renaming the file or by copying.
Renaming means that Emacs renames the existing file so that it is a backup file, then writes the buffer into a new file. Any other names that the old file had will now refer to the backup file. The new file is owned by you and its group is defaulted.
Copying means that Emacs copies the existing file into the backup file, then writes the buffer on top of the existing file. Any other names that the old file had will now refer to the new (edited) file. The file's owner and group are unchanged.
I prefer to have the files backed up into 1 directory
(setq backup-directory-alist '((".*" . "~/.Trash")))