Occasionally, Chrome OS can't recognize when a wireless keyboard and mouse is attached and will automatically pull up the on-screen keyboard. In order to stop this from happening, you can follow the steps below and it should correct the issue.
- Open your browser.
- Copy and paste or type chrome://flags#enable-virtual-keyboard into the URL bar.
- Set the highlighted setting to disabled. You may be asked to relaunch your browser.
- Copy and paste or type chrome://flags#disable-virtual-keyboard into the URL bar.
- Set the highlighted setting to enabled. You may be asked to relaunch your browser.
This should correct your issue and disable the on-screen keyboard.