Please, check MetaMask plugin and keys section
Please, check Ceremony section.
To check, who are already have authority in Oracles network, go to Validators Dapp.
Joining to the Oracles network is managing by Governance Dapp.
Please, check Governance section.
If you want to create a separate network based on Oracles, please use this Boot node setup guide to setup your own Oracles network.
To delete the mining node that you've created previously during Ceremony, please refer to this guide. Note that if you want to create mining node later again, you'll need to reuse your existing mining keys, you won't need to generate production keys again.