Use the tweaks app on youriPadoriPhone, or System Preferences on a Mac, to disable Siri.
Confirm withTurn Off Siri.
On the message prompt about Dictation remaining on Apple’sservers, tapTurn Off Siri.

See the instructions below if you don’t turn off Dictation at this step.
Go toSettings>General>Siri, and toggle offSiri.
TapTurn Off Siriwhen asked to confirm your choice.

Disabling Siri on iOS 10 also turns offAllow “Hey Siri”.
This is also necessary if you wish to remove all of your voice data from Apple’s servers.
Turning off Dictation is the same on iOS 12, 11, and 10.

Go toSettings>General>Keyboard.
Scroll to the bottom of the screen and turn off theEnable Dictationtoggle switch.
In the confirmation box, tapTurn Off Dictation.

How to Disable Siri on macOS
Disabling Siri on a Mac is also fairly straightforward.
Go to theApplemenu and selectSystem Preferences.
Clear theEnable Ask Siricheckbox.

This turns everything else off, including removing the Siri icon from the menu bar.
For that, you have to turn off dictation.
Go to theApplemenu, selectSystem Preferences, chooseKeyboard, then select theDictationtab to turn the feature off.