Lunar Magic: Super Mario World Level Editor Tool
Lunar Magic is an editor made by FuSoYa for Super Mario World editing.
It has many features and is an extremely advanced editor.
Lunar Magic WIKI
Also Here is Yy-chr Program
YY-CHR is a program that allows you to edit the graphics of a ROM until you see fit.
The tool can edit a large quantity of graphics from various gaming programs ranging from GB to SNES.