How can I disable hotspot on my phone

Settings > Personal Hotspot > Personal Hotspot = "Off"

If you mean restrict personal hotspot so someone (like a child) cannot turn it on, consider:

• Settings > General > Restrictions > [Allow Changes] Cellular Data = "Off" along with Settings > Cellular > Cellular Data = "Off"
• Asking your cellular carrier to disallow hotspot on this telephone number.

You should immediately stop using the same Apple ID as your daughter. This will cause other issues if it hasn’t already.

Thoroughly cleanse any device she uses before settling it up with her new Apple ID.

https://support.apple.com/en-us/HT201351

Set up her Apple ID and Family Sharing, even if she is a child.

https://support.apple.com/en-us/HT201084