My iPad automatically connect to my iPhone hotspot and is using up my data

Hi,

My kids use my iPad a lot and it seems to often automatically connect to the hotspot from my phone. I've even changed the password on my phone, and keep turning the hotspot off but it doesn't work - the iPad seems to just know my password whenever I reset it. How can I fix this? I'm happy to never use the hotspot on my iPad, as I never really need it.