I have a late 2010 11" Macbook Air with a 1.4 Ghz Intel Core 2 Duo and 2 GB of RAM. I have no replacement parts installed, it is all original. I installed ChromeOS Flex on it to give it life again, but I don't really like it now and regret installing ChromeOS. Whenever I try to go to recovery mode it does not work, it just boots into ChromeOS Flex, and my reinstallation drives are not detected in startup options. How do I uninstall ChromeOS Flex and get back to Mac OS X El Capitan?