Hello,
After looking into it, it seems your KMS trial account had the demo option set to true.
When demoMode is set to true, logging in with any user and passwd combination, will trigger a creation of this user and setting it to admin role.
This can be disabled from the KMS admin UI, by going to the "Auth" section where you can set this option to off.
This was already done for you account.
You can also read about this option here:
https://knowledge.kaltura.com/sites/default/files/Kaltura_MediaSpace_Setup_Guide_5_50_0.pdf
Thanks,