import re

test_str = ("(a) method in/to one's madness\n"
    "(all) by one's lonesome\n"
    "(as) tough as (old boot's)\n"
    " (at) any moment (now)   \n"
    "factors (in or into or out)        \n"
    " right-to-life\n"
    "all mouth (and no trousers/action)\n"
    "(it's a) small world\n"
    "  throw (someone) a bone ")

regex = r"[^\S\r\n]*\([^()]*\)"
result = "\n".join([x.strip() for x in re.sub(regex, "", test_str).splitlines()])
print (result)