Dark grey bar at the bottom of Chrome in iPad
You cannot remove that grey bar because it's an area of the virtual toolbar with additional tools that  will appear like Undo/Redo, Cut, Copy, and Paste. The "up and down arrows" is like hitting Tab and ShiftTab to cycle between fields on the webpage.  It usually doesn't show unless there are fields to navigate or items in the clipboard.

It appears in Firefox, Safari and Brave browsers as well.