Let’s Encrypt is trying to perform a Domain Validation challenge called TLS-SNI-01
It connects to your HTTPS server, and says it wants to talk to a server with this unlikely looking name ending in .acme.invalid, it does this as part of the challenge.
Your HTTPS server has no idea what this is about, and responds with a default of some certificate you already had. It won’t help you to “delete” this other certificate. To pass the challenge your server would need to give the correct answer, giving no answer at all, or a different wrong answer won’t help.