Close Project    ⌥⌘W

Close the current project. If there are any unsaved changes Logic will prompt you to save the changes.

‘Close Project without saving’ is ⌃⌥⌘W

Save Logic Pro projects — Apple Support

Logic Pro autosaves your work so that you don’t lose important changes if the app quits unexpectedly. Logic Pro shows a dialog when you reopen the project, asking if you want to use the autosaved version. If you choose not to, Logic Pro opens the last manually saved version of the project.