Sure, just make sure you don't click on Uninstall button, only use the Deactivate and Delete buttons. After deleting and installing it again, you should delete all caches and press Ctrl+F5 on forum front to load customized colors.

@Robert, I did all that and the file is not there. The color does not come back. Where is the color scheme stored in the database?

I can see these tables:

Very strange, but it's working now. I reinstalled twice, changed the color in the backend and it worked. I have my colors back. 

I did not change original directory permissions. I don't get it, but it works.  😀 

That's great news gombi1!

It seems some process was affecting colors.php file and it was not writable.