add delete endpoint

Services/FileNoteService.cs

@@ -32,6 +32,13 @@
             File.WriteAllText(GetFilePath(noteName), content);
         }
 
+        public void DeleteNote(string noteName)
+        {
+            var filePath = GetFilePath(noteName);
+
+            File.Delete(filePath);
+        }
+
         private void CheckFile(string noteName)
         {
             var filePath = GetFilePath(noteName);

Services/INoteService.cs

@@ -5,5 +5,6 @@
         ICollection<string> GetNoteNames();
         string GetText(string? noteName);
         void SaveText(string content, string? noteName);
+        void DeleteNote(string noteName);
     }
 }