Android Questions? Ask Android Device Experts for Answers ASAP
Hi there and welcome
Open up Messenger (it is the app called messenger with the lightening bolt in the blue speech bubble)
Then press on the photo in the top right
Swipe down and choose Switch Account
You can then sign in with your account and remove theirs there.
Let me know how you go please.
No, accounts do not get attached to phones as such, it is just when you sign in that you then get the messages.
Now that you have signed out it stops any link