Article in English: You can delete your recent searches from within the Safari browser. If you are using an older version of Safari with a separate Search bar, click the Search bar instead. This should ensure that your recent searches are displayed. This only clears your recent searches. If you need to delete all of your browsing history, click here. If you only want to remove a single search history entry, you can do so from the Bookmarks view.  Click the Bookmarks button or press ⌥ Opt+⌘ Cmd+2. Search for the entry that you want to remove. Select the entry and press Del or right-click it and select "Delete".

Summary in Vietnamese:
Mở Safari. Nhấp vào thanh URL. Xóa URL đang hiển thị trong thanh. Nhấp vào tùy chọn "Clear Recent Searches" (Xóa tìm kiếm gần đây) ở cuối danh sách. Xóa mục nào đó.