How to remove grey bar from bottom of page (including space tools gear menu from sidebar)

[Crystal Pacheco]

I would like the grey bar at the bottom of the page to be invisible. Including the "Space tools" grey gear box menu at the bottom of the sidebar.

I'm on the default theme, there's no CSS variable that I can say display:none;

I was unable to find floor.png . 
Working as an admin in the dashboard. Where can I edit in the Look and Feel menu to remove the grey bar?

[Nic Brough -Adaptavist-]

There is no real way to do this.  And you would be breaching the terms of your contract - you are required to keep "powered by Atlassian" displayed in the footer.