I can't find an "open" app that must be closed

I'm having many, many problems trying install the app1PASSWORD. Now decided to trash every file I can find with its name and start over. But now, one file with the apps name can't be found to close. When I try to delete it by sending itl to trash, a message pops up saying the app can't be sent to trash because its open. Trying all usual methods I know and can't find app to close it. Please help