Excel Short & Sweet Tip #5 (Hiding Error Triangles) by David Hager

Would you like a way to remove those green error checking triangles from worksheet cells, yet retain error checking? Go to File, Options, Formulas, Error Checking. Leave the “Enable background error checking” box checked, and change the Indicate errors using the color (default is green) to white. Of course, this only works if the cells are white. To turn off the error checking and the green triangles, change the “Enable background error checking” box to unchecked.