It sounds like the app that you accidentally activated as a device admin has some security policies in place that prevent you from revoking its device admin privileges. This can be a common issue with apps that are designed to have heightened security measures, such as those used within the Secure Folder.
Here are a few steps you can take to try to remove the device admin privileges from the app:
First, try restarting your device. Sometimes this can help clear out any temporary issues that might be preventing you from revoking the device admin privileges.
If that doesn't work, try going into the Secure Folder settings and looking for an option to remove the device admin privileges for the app. This option should be under "Security" or "Device Administrators." If you don't see an option to remove the app's admin privileges, it's likely that the app has taken full control of the Secure Folder and you may need to reach out to the app's developer for assistance.
If you're still unable to remove the app's device admin privileges, you may need to factory reset your device. This will wipe all data from your device, including the Secure Folder, so be sure to back up any important data before proceeding.
To factory reset your device, go to "Settings" > "General Management" > "Reset" > "Factory data reset." Follow the on-screen instructions to complete the reset process.
Once your device has been reset, you can set it up again and reinstall the Secure Folder. Be careful when activating device admin privileges for any apps in the future, and be sure to only give admin access to apps that you trust and understand the security implications of.
