The support chat bubble has a small × in its top corner. Click the × and the bubble disappears, along with the chat if it's open. It stays hidden for as long as that tab is open, even if you navigate to other pages in Ads Editor. To bring it back, close the tab and open Ads Editor in a new tab. Your conversation isn't lost: when you open the chat again, it's still there.

On the plans screen (Plans and Payments), the green WhatsApp button (Contact us on WhatsApp) also has an × and works the same way: it disappears until you close the tab.

This is mainly useful on phones, where the buttons can cover part of the content.