You will also have to replace the copyright "Powered by ...." notice that you have removed from the bottom of your forum
Agreed, however he is not in violation of MOVING/REMOVING it, he's in violation of MASKING it...
Quoting the Licensing Agreement
which you agreed to by purchasing/renewing your license:
2. Copies; Notices. Except as provided in this Section 2, a separate license is required for each additional bulletin board instance. You may make a reasonable number of copies of the Software solely for emergency back-up, testing or archival purposes. These copies must not be publicly available. Further, You may load the Software onto another CPU server owned or operated by You on a hot "redundancy" basis. The ultimate result must be only one publicly accessible instance of the message board per license. [qb]The "Powered By" legend in the HTML title may be removed; however, the copyright and "Powered By" legends at the bottom of each page may not be removed. You may modify the positioning and colors, and/or remove the hyperlink to the Groupee website, as long as the legends remain readily perceptible to the human eye.[/qb] Beyond these specific stipulations, You may not alter any proprietary notices and legends of Groupee that are contained in the Software, within the scripts and HTML generated by the scripts, and related documentation as delivered under this License. You acknowledge that any unauthorized removal or modifications of these notices or legends is a breach of this License.