Backup your website content, then unlink your parked domain. Go to your domain management page with your registrar and change the name servers back to default (contact your registrar is you don’t know what they are). Then, set a CNAME record for [yoursite].000webhost.com for @ (or leave it blank, depends on your registrar). Next, on your 000webhost site control panel, add the domain via point (CNAME) when the record is propagated.
Then, on your domain management page with your registrar, change the name servers to the Cloudflare name servers provided when you follow my tutorial above (not the ones in the screenshot, but on your actual Cloudflare page). Then follow the tutorial.