No, you can't remove it because that's the way to prevent you using the full software since it hasn't been purchased. Once you acquire the full version of the software, all the limitations, nag screens, watermarks and everything will be removed and then you can fully use it on your PC.
I've checked the website, and you've downloaded a trial version that its limited through watermarks on your forms.
You need to purchase the full product to remove the watermark, else it won't be possible.
