Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. https://crt.sh/?q=example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.
You don't need to remove the old explicit. Install the new, then the old is replaced. And an expired certificate is better then no certificate, "no certificate" may break your webserver.
But I don't know how to install a certificate in Litespeed. There must something going wrong.