As i saw sometimes even if you bought this plugin for wordpress you can't delete logo.
Let's do something with this - You need SWF Decompiler like Sothink SWF Decompiler or another.
Download plugin archive - unzip or untar - find hdplayer.swf and open in decompiler.
Expand tree with images and just edit all that contents "free" and "demo" with your logo or 1x1 pxel transparent image. Save and replace swf in your folder.