To reset your server completely, you can stop the server, log in via FTP, then delete all of the files except for the eula.txt file. After the files are deleted, set the server to use Vanilla Minecraft in the control panel, save it, then start the server. When the server is started without files, new server files will be created. You can read our FTP (FileZilla) guide here: https://www.hosthorde.com/forums/resources/getting-started-with-ftp.31/
