Hi @betijakaire,
You have asked the same question on past and Yongki has replied you! : Delete the chat only for logged in user - #2 by Yongki
Another option would be using a Many to Many relationship that adds Logged in user there when the user clicks the delete button and filter the conversations list that Current Conversation > Removed Users ( many to many rel ) > Does Not Contain > Logged in user.
Thank you
P.S. - Your topic’s heading tells a one question and your content inside the topic tells another question. Maybe changing it to a one question will be great and then the community can understand your issue well and help you!