I'm happy to be corrected on this but it is my understanding that by converting a RAW image to a Digital Negative (DNG) you merely shrink the file size by up to 20% with no loss of information. For all intents and purposes it is still a RAW file, it is just that adobe's "RAW" file is called DNG and it enables you to store the data more efficiently, hence the smaller file size.
Therefore, whilst I understand you can store metadata within a DNG file, the actual image will still detail everything that was originally taken. That is the whole point in a digital negative; it is the equivalent of an old analogue film negative.
So, to conclude, any trademarks that were in the original shot will still be contained in the DNG.
Like I've said though, I am happy to be corrected on this.
In Digital Photo Professional DPP for RAW Canon is stamp tool. But stamp tool can affect only when you open stamp tool or do export to JPG. Buyer can see logo, even if you delete logo by stamp tool in RAW. If buyer wants to know, what logo was removed, then buyer will ask RAW additonal format.
f/2.8L IS , 50 mm f/1.4, 100 f/2.8, Sigma 12-24 f/4, Glidecam 2000 Pr...