feat: finish highlevel unregister

wfassoc/src/highlevel.rs

@@ -485,7 +485,31 @@ impl Program {
     /// No matter whether there is registration of this application,
     /// this function always make sure that there is no registration after running this function.
     pub fn unregister(&mut self, scope: Scope) -> Result<(), ProgramError> {
-        todo!()
+        // Delete App Paths subkey
+        debug_println!("Deleting App Paths subkey...");
+        self.app_paths_key.delete(scope)?;
+        
+        // Delete Applications subkey
+        debug_println!("Deleting Applications subkey...");
+        self.applications_key.delete(scope)?;
+
+        // According to Microsoft document, when uninstalling application,
+        // it is enough that only delete ProgId keys.
+        // Programmer doesn't need to edit something in Ext keys.
+        // So we delete ProgId subkeys one by one in there.
+        debug_println!("Adding ProgId subkey...");
+        for program_progid_key in &mut self.ext_keys {
+            let progid_key = &mut program_progid_key.progid_key;
+            
+            // Delete ProgId subkey
+            debug_println!("Deleting ProgId \"{0}\" subkey...", progid_key.inner().to_string());
+            progid_key.delete(scope)?;
+        }
+        
+        // Everything is okey.
+        // Notify changes and return
+        win32::utilities::notify_assoc_changed();
+        Ok(())
     }
 
     /// Check whether this application has been registered in given view.