Q: Preparing to delete trash keeps going

I tried to back up my hard drive, (running Yosemite) using Super Duper.  It said it could not back up because something in the trash wouldn't go. I had earlier removed a virus threat and thought perhaps it hadn't been deleted.   I tried a secure delete and it keeps preparing to empty and at the moment says there are 2.5 MILLION items and rising.  What do I do!! Thanks.