As per the Google Map Terms and Conditions section 8.4 b viii
Restrictions. In using Google Brand Features, you will not:
remove, distort, or alter any element of a Google Brand Feature
(including squeezing, stretching, inverting, or discoloring).
and section 8.5
Proprietary Rights Notices. You will not remove, obscure, or alter any proprietary rights notices (including copyright and trademark
through the Service. Where such notices are not displayed or provided
within the Service, you must display such notices according to the
Maps APIs Documentation.
So in short it is illegal.