To detect rooting status of device, an app issues
su command. If exit status is
0, it means device is rooted.. otherwise, not.
To prevent this, you can simply
Deny the root access using SuperUser's pop-up (Provided its allowed from SuperUser settings, a pop-up appears when an app issues
su command). After this, the app will get
non-zero exit status & it can't determine rooting status.
Some apps can use other ways to check root status (like checking the
su binary file existence). I'd like to admit that none are perfect methods without false-positive result, but sometimes they are successful with luck.
The best universal method to prevent detection: Restrict the permission of app's daemon. I can't suggest exact permission limitations because I don't know functions of the app. It can mess up with app's functionalities.
In the last, I'd like to say: Technically, there's no way to prevent detection by 100% success rate. In case of permission limitations, the app can still suspect that something is wrong.