import re
strs = ['1/26/2009through', 'through1/26/2009']
for s in strs:
res = re.sub(r'\d{1,2}([/,:])\d{1,2}\1\d{2}(?:\d{2})?', '', s)
print("{} => {}".format(s, res))
aW1wb3J0IHJlCnN0cnMgPSBbJzEvMjYvMjAwOXRocm91Z2gnLCAndGhyb3VnaDEvMjYvMjAwOSddCmZvciBzIGluIHN0cnM6CglyZXMgPSByZS5zdWIocidcZHsxLDJ9KFsvLDpdKVxkezEsMn1cMVxkezJ9KD86XGR7Mn0pPycsICcnLCBzKQoJcHJpbnQoInt9ID0+IHt9Ii5mb3JtYXQocywgcmVzKSk=