Oppo
Turn On/Off Device Administrators auf Oppo
Some apps ask for device administrator rights to perform deep system actions: locking the screen remotely, wiping all data, or enforcing password rules. Google's Find My Device is the most common example, and it's active by default on most Oppo phones.
Once an app holds device admin rights, Android blocks a normal uninstall. You get a warning that the app is an active administrator before you can remove it. Revoking that permission first is what actually solves the problem.
Turn device admin apps on or off
Open Settings ➔ Security ➔ Device admin apps. Enter your verification code and tap Activate if asked, then pick the app from the list and tap Activate or Deactivate.
Deactivating an app here only removes its administrator access, it does not uninstall the app itself. Corporate mobile device management (MDM) profiles and some security apps will stop working correctly once deactivated, so only turn off admin rights for apps you actually recognize and no longer need.