import re
s = "refer- ences har- ness Stand- ard Re- quired www.mypo- rtal.test.com A - it is a document, move- to store"
print(re.sub(r"(?<!\s)-(?:(\s)+(to)\b|\s+)", r"\1\2", s))
aW1wb3J0IHJlCnMgPSAicmVmZXItIGVuY2VzIGhhci0gbmVzcyBTdGFuZC0gYXJkIFJlLSBxdWlyZWQgd3d3Lm15cG8tIHJ0YWwudGVzdC5jb20gQSAtIGl0IGlzIGEgZG9jdW1lbnQsIG1vdmUtIHRvIHN0b3JlIgpwcmludChyZS5zdWIociIoPzwhXHMpLSg/OihccykrKHRvKVxifFxzKykiLCByIlwxXDIiLCBzKSk=