First, open Finder, select Go menu (on the menu bar) > Go to Folder, and type ~. Do you see an Applications folder? If so, it's easy. If you don't have the folder, you can put the app in any other folder, or create the Applications folder. To do it, press Shift, Command and N keys, and type "Applications", and open this folder
Now, open a new Finder window by pressing Command and N keys. In this window, choose Applications in the sidebar, and copy the app to the window where ~/Applications is opened.
Do the same with the rest of the users. Finally, delete the app in /Applications. Note that this only works for some apps, because there are some apps that can only be stored in /Applications. If you are not sure if yours will work, leave it in /Applications. Nothing will happen if one user doesn't need the app, as you will not be wasting space