Confluence is installed at /opt/atlassian/confluence in CentOS environment, and the home directory is usally installed at /var/atlassian/application-data/confluence that is known as home directory. To reset confluence, what you should do is simply reasing home directory.
If you installed your confluence server in default directory, you can simply reset your confluence by erasing the home directory like below:
sudo rm -rf /var/atlassian/application-data/confluence