import re
inputString = "I want to remove <code>tag with space</code> not sole <code>word</code>"
outputString = re.sub("<code>(.+?)</code>", lambda m: " " if " " in m.group(1) else m.group(), inputString, flags=re.S)
print(outputString)
aW1wb3J0IHJlCmlucHV0U3RyaW5nID0gIkkgd2FudCB0byByZW1vdmUgPGNvZGU+dGFnIHdpdGggc3BhY2U8L2NvZGU+IG5vdCBzb2xlIDxjb2RlPndvcmQ8L2NvZGU+IgpvdXRwdXRTdHJpbmcgPSByZS5zdWIoIjxjb2RlPiguKz8pPC9jb2RlPiIsIGxhbWJkYSBtOiAiICIgaWYgIiAiIGluIG0uZ3JvdXAoMSkgZWxzZSBtLmdyb3VwKCksIGlucHV0U3RyaW5nLCBmbGFncz1yZS5TKQpwcmludChvdXRwdXRTdHJpbmcp