How can I cancel a conversation on Facebook Messenger?

There has already been a question like this, but it is out of date or I see a particular case.

I have ignored someone on Messenger and I wish to cancel it without sending him a message. When I open their conversation from filtered messages in the browser version of Facebook, there is no Answer / Delete option. When opening the conversation in the Messenger application, it gives me only one option: "I do not want to hear from [name]"

If I meet this scenario, how can I cancel an ignore?