Remove welcome message
How to remove Welcome Message (above the Chat Bubble Icon)
If you don't want this little text box to appear along with your chat widget. You can check the settings in the Facebook Inbox Settings.
Go to FB Business Suite (https://business.facebook.com/latest/inbox/settings/chat_plugin) > Customize Your Chat Plugin -> Prominence -> Button
In the Button display section, decide how the chat button will look (Icon Only) In Prominence, please select Button
Good to know: You can change the bubble appearance so it is unable to hinder other sections in product page.