To disable the developer options on the Xiaomi smartphone, simply navigate to the menu and flip the switch, and the developer options are hidden after entering in settings again.

Android 10 (MIUI 12.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Additional settings
Step 3:  Tap on  Developer options
Step 4:  Disable  Developer options
Step 5:  Tap on  Back
  1. Open the Settings
  2. Tap on Additional settings
  3. Tap on Developer options
  4. Disable Developer options
  5. Tap on Back

Xiaomi Instructions