Work through these in order. Step 1 solves it in almost every case, and you can always unlock your child's phone without our help.
This is the fastest fix and it works even if your child's phone is in your hand or across town.
TaskKidz → Settings → find your child under "Kids in Family" → Release deviceThe phone unlocks within a few seconds, as long as it has mobile data or Wi-Fi. If nothing happens, the phone is probably offline — see step 2.
TaskKidz needs a connection to receive the unlock. If the phone is in aeroplane mode, out of data, or has no signal, the release cannot reach it.
Once the phone is back online it will pick up the release on its own. You do not need to press anything again.
If you have the phone in your hands and want it unlocked right now, you can switch off the TaskKidz device administrator directly. This ends all locking on that phone immediately.
Settings → Security and privacy → More security settings → Device admin apps → TaskKidz → DeactivateWording varies slightly between Android versions and brands. Look for "Device admin apps", "Device administrators", or "Phone administrators" under your security settings.
Nothing is lost by doing this. Chores, balances and history all stay exactly as they are, and you can switch locking back on later from inside the app.
If you would rather remove the app entirely, deactivate the device administrator first using step 3, then uninstall as normal. Android will not let an app with device admin active be uninstalled until it is deactivated.