If you don’t want to go the folder route you could hide them via a CSS snippet.
div[data-path$='.png']{
display: none;
}
If you do go the folder route and want to hide the folder you can do that too, just replace assets with the name of your folder:
div[data-path$='assets'],
div[data-path$='assets'] + div.nav-folder-children
{
display: none;
}
See this post it’s where I got it: Show / hide file types to be shown in file explorer