Select your Settings app on your iPhone.
Scroll down your iPhone's Settings, until you see Siri & Search. Select it.
In this menu, you can turn off Siri by toggling off all of the buttons, or you can toggle on and off the individual Siri features that are giving you trouble.
Here's what each one means:
- This command allows you to verbally say "Hey Siri" to activate Siri. Siri will then respond to the next set of commands your speak after that.
- This allows you to press and hold the right button of your iPhone to activate Siri.
- This feature allows you to activate Siri even when your phone is locked.
I recommend you deactivate #3. This will make it so that Siri will not just turn on randomly when you're not using your phone. I like keeping on #1 because I use my phone when running, and I can use Siri to adjust the volume of my AirPods.
You probably use your backspace [delete] key quite a bit.