How can I delete this app?
Same as anything. Put it in the trash and empty it.
Remember that you make have photos managed by it so be sure you know what you're doing.
I did it but it doesn't work.
It works okay but you seem to have a very different problem.
Are you trying to Quit the app? Or Delete it?
Force Quit is under the Apple Menu.
I tried to close the app but it didn't work so I thought that I could closed it if I delete the app...
ooohhh.. I saw it!
Retrieving data ...