How to send a normal message without it going right away to iMessage?

My friend had a iPhone and now they have a Samsung and I will try to text them but it will just go straight to an iMessage when I want it to go to text message. How do I fix that without having to go to settings and turning off iMessage for everyone?

You can either turn off iMessage in the settings under (you guessed it) iMessages or your cellular data in the settings under (you guessed it again) cellular data

Suggest your friend to deregister their number here from iMessage: https://selfsolve.apple.com/...r-imessage