Anchor ads, either sticking on top or bottom, is pretty annoying to me because it sometimes messes up with the navigation bar or other important messages. Further more, It takes pretty much space on mobile devices.
You can completely disable all anchor ads, both top and bottom by
- Go to Ads > Overview > By site and click on the Edit icon next to your site
- Disable the Auto ads option in the Site settings to disable Auto ads completely on that site.