Hi Immanuel,

Thanks for reaching out to us. You can use this custom CSS code to hide the image 

#amelia-container > div.am-fs__main > div > div.am-fs__main-content.am-fs__congrats.am-fs__main-content > div.am-fs__congrats-main > img {
display:none!important
}

Custom code needs to be applied to the page where the booking form is. Depending on what you're using (Gutenberg blocks, or some page builder), adding the CSS or JS can be done in a few different ways. 

If you need help with adding custom CSS to the page, please take a look at this article.

Please note that I've had to book a test appointment, so you want to remove this to avoid confusion

Please, let me know if it works.