fname = "test.txt"
    with open (fname, encoding='utf-8') as f:
        old_data = f.read()
        new_data = old_data.replace('thrash1', 'word')
    with open (fname, 'w', encoding='utf-8') as f:
        f.write(new_data)
    print("Delete thrash")

 for wd in ["trash1", "trash2"]:
    old_data.replace(wd, 'word')
new_data = old_data.replace('thrash1', 'word').replace('thrash2', 'word')...