how do I get rid of this google searchbar?
The search bar is a built-in part of the default launcher and can't be moved or disabled. The least invasive way to get rid of it is to install a new launcher of your choice and use that instead of the default one. The old launcher is still installed, and will come back when you uninstall the new one, so the question is just whether you ought to install software on this device you've borrowed.