A “sticky” ad appears on the mobile version and I can’t remove it

The ad is displayed in the navigation bar of my website. I tried to exclude this zone so that the automatic ads do not add it, but I cannot remove it. The ad stays on and takes up the entire screen, even when I scroll down.

This only happen in the mobile version of my website. This is an example of the situation: https://imgur.com/a/zS8n8B6