How to delete SSL certificate?

By using the below command, I’ve created an SSL certificate. As the common name, I’ve given the IP address of the server.

openssl req  -new  -newkey rsa:2048  -nodes  -keyout localhost.key  -out localhost.csr

And using the below, I’ve signed by myself.

openssl  x509  -req  -days 365  -in localhost.csr  -signkey 
localhost.key  -out localhost.crt

After all, I’ve realized that I’m unable to use an SSL certificate with just an IP address as a common name. This way, the browser does not trust my certificate because it’s signed by me. What I want to do is to revert this process. I’d like to keep using http as I’ve been doing before. How can I remove the SSL that I’ve created in this process?

OS: Ubuntu 18.04 LTS