I wasn't the person who implemented the V3 client and I haven't had the chance to use it more thoroughly yet.
If you bought a paid subscription to Craiyon.com, you would know that the watermark is removed. If you wish to have the watermark removed from the generated images in your application as well, you can specify a token here.
To find your token: Open Google Chrome, go to craiyon.com (make sure you're logged in), Press F12, go to the Network tab, make sure the record button looks like a red circle at the top-left. Put your prompt in the text box and press the orange "Draw" button. Two "draw" items should appear on the left, under "name". One of them will have a "Payload" tab next to "Headers" and "Preview", as well as above "General". Click it, and your token is listed there.
I wasn't the person who implemented the V3 client and I haven't had the chance to use it more thoroughly yet.
Source: https://github.com/FireHead90544/craiyon.py#api_token