How to enable:
Go to the [Settings] app on your phone/tablet >> [About phone/tablet] >> [Detailed info and specs] >> tap [OS/MIUI version] multiple times to enable the developer options.
You can go to the [Settings] app on your phone/tablet >> [Additional settings] to check the developer options entrance.
How to disable:
Go to the [Settings] app on your phone/tablet >> [Additional settings] >> toggle the [Developer options] switch to hide the developer options.
Note:
When using the [Security] app to optimize, the developer options entrance will be hidden.