After further discussing this with our development team, it looks like the background image must be modified manually (e.g. removing the watermark).
After modifying the image, please go to "Themes"
page --> "Images"
tab --> replace the glassbackgroundsmall.png
with the modified one.
The above image can be found in the following location:
C:\Program Files (x86)\Caphyon\Advanced Installer 17.8\themes\common-res\frame
For instance, if you are using the "Air --> Air"
theme, the imagine is found in the following location:
C:\Program Files (x86)\Caphyon\Advanced Installer 17.8\themes\common-res\frame\powderblue\rtlo-glassbackgroundsmall.png
Hope this helps!