Text messages going to husband old number even though it’s not saved anymore

I tried texting my husband and it went to his old work phone, he doesn’t work with that company anymore so he doesn’t have that iPhone. I deleted that number from his contact, then when I tried texting his regular phone (non iPhone) it changed his number to his old work phone number and sent it as an iMessage. I tried turning off iMessage for an hour and restarted my phone, and I don’t have messages or contacts linked to my iCloud at all. Some random person who has that phone now is now getting iMessages from me and I can’t figure out how to fix it.