You can delete core using the delete command of Apache Solr.

Let’s suppose we have a core named my_core in Solr, as shown below :

You can delete this core using the delete command by passing the name of the core to this command as follows :

solr delete -c my_core -p 8983

On executing the above command, the specified core will be deleted displaying the following message.

You can open the web interface of Solr to verify whether the core has been deleted or not.