How about turning out the light ?
Sorry, I couldn't resist !
It's very little information you give us - do you have a picture ?
An obvious solution would be to rearrange your lighting. Perhaps a second light at an angle to eliminate the shadow.
Another would be to change the backdrop behind the sign. Place part of a building cutout behind the sign so that the shadow falls on this. It's OK if a shadow falls on another building; it's not OK if the shadow falls on blue sky or clouds.
Hope this helps,
Jim Policastro
Jim has some great ideas there . I might add I have used trees with flat backs right up against the backdrop in some of these situations.
Mike
“When I was 5 years old, my mother always told me that happiness was the key to life. When I went to school, they asked me what I wanted to be when I grew up. I wrote ‘happy’. They told me I didn’t understand the assignment, and I told them they didn’t understand life.” -- John Lennon