That app is using the Samsung Knox api, which cannot be disabled by you. You need to reach whoever installed it and ask him to enable you permission to deactivate device admin. Another option would be wipe, if that is not locked too. You can check that by going into Setting - Backup and reset. If its grayed out, there is nothing you can do.
AS EXTRA, i can say the samsung api can lock device admin removal, factory reset from system and recovery and also flash through download mode and also safe mode.
I am using the same api in some of my apps and i know what that means. I cannot show now the link to it as Chrome is freezing on mobile. Will do when i get to my pc.
public boolean setAdminRemovable (boolean removable)
An administrator can set their removable status. If set to true, the user can remove the administrator through the Settings application. If set to false, the user cannot remove the administrator through the Settings application.