dconf-editor, and open:
org -> gnome -> desktop -> interface
nautilus, select any file/directory, then click "Edit" from menubar, and hover on "Move to Trash" menuitem. While hovering, click on your delete key. The accel should change from "ctrl+del" to "del".
Make sure you have selected a file, else the "Move to Trash" menuitem will be greyed out.
NOTE: I suggest you disable "can-change-accels" afterwards, to prevent accidental accel changes.
If the above doesn't work take a look at this archlinux wiki article on how to change your hotkeys in Gnome 3.x. This article has specific steps for a couple of versions of Nautilus.