On ServiceNow Platform Connect Support, when the user clicking 'End Chat' before the agent is accepted the request, the "You have closed this support session. "Rejoin the session" link will be show up and allows the user to reopen the chat by click the link. At the same time the State for the chat_queue_entry record is in "Closed Abandoned".
If you want to remove the "Rejoin the session" link on the Chat window, you can follow suggested steps in the Procedure below.
Please keep in mind that this article falls beyond the scope of support as it is a customized implementation. Below are just suggestions for reference which we have provided here to help solve similar issues.