import re
regex = r"\bwhere(?:(?:(?!where)[^][])*\[[^][]*])+\s*"
txt = ("where this condition and [this = 1] group by 1,2,3\n"
"where that and that do that where [this = 1] and [that = 1] group by 1,2,3")
result = re.sub(regex, "", txt)
print (result)
aW1wb3J0IHJlCiAKcmVnZXggPSByIlxid2hlcmUoPzooPzooPyF3aGVyZSlbXl1bXSkqXFtbXl1bXSpdKStccyoiCnR4dCA9ICgid2hlcmUgdGhpcyBjb25kaXRpb24gYW5kIFt0aGlzID0gMV0gZ3JvdXAgYnkgMSwyLDNcbiIKCSJ3aGVyZSB0aGF0IGFuZCB0aGF0IGRvIHRoYXQgd2hlcmUgW3RoaXMgPSAxXSBhbmQgW3RoYXQgPSAxXSBncm91cCBieSAxLDIsMyIpCnJlc3VsdCA9IHJlLnN1YihyZWdleCwgIiIsIHR4dCkKIApwcmludCAocmVzdWx0KQ==