import re

pattern = r"\[.*?\]|(\d+)"

s = "[Verse 1: Bankroll Fresh] Dope boy, '[9]5 Air Max on Came from 1952.."

print(re.sub(pattern, lambda x: '' if x.group(1) else x.group(), s))

print(re.sub(r'\[?\D*(\d+)\D*\]?', lambda x: x.group(0) if x.group(0).startswith('[') else x.group(1), s))