I have denied the permission to use the Asset Manager in the configuration of the service of the Web Report Designer. This is generally respected and I do not see the option to open the asset manager from the main menu but when I try to set an image to a PictureBox item, I still see the option to add it from the assets and the button is also clickable.
With that being said, the permission is respected on the server and I get an error about not having permission to use the Asset Manager when I click on the button. Still, it will be better if the button is removed from the UI altogether when I have disabled the assets.