thanks, I think if you select another one or click again on the same tower it goes away, but yeah thats a bug. Probably the best way to get rid of it is post here and shame me to go back and fix some bugs :D. Thanks for playing.
I noticed this too and actually figured out how to click out. You just click on the ground. If it's not the one you wanted to get rid of, click on the one you want to disable and then click on the ground and it will go away. While this was annoying at times, it was also useful to see if two towers overlapped and fix it if they didn't. So I'd suggest keeping it the way it is or making it so you can have it stay if you want it to.