从Plesk添加域名到Cloudflare时报如下的错误，确认过没有任何的Cloudflare账号绑定过这个域名，而且自己的Cloudflare账号是可以添加和删除这个域名的。
Cloudflare is already activated for “xxx.com” under a different account. If you want to enable Cloudflare through this partner, please log in to your Cloudflare account and choose “Disconnect” on your Cloudflare DNS Settings page.
最终原来是在百度云加速里添加了这个域名，把百度云加速域名删掉就好了。百度云加速和Cloudflare也是合作伙伴。