I accidentally hit restore while phone plugged into computer. Now my ICloud email is now the person who my old phone belonged to. Not even this phone! So now I can’t enter my OWN iCloud password pleas help !!!!!

How can I get rid of this random iCloud on my phone that it was never on in the first place. My man has his iPhone 4 plugged into computer which had this iCloud on it. I unplugged it and plugged my phone in. I’m doing so I accidentally hit restore. Now I have that iCloud email address on my phone. Obviously I don’t known the password and I can’t get it back to my iCloud that’s always been on this phone. How do I fix this!????? Please help. I’m desperate.