Support delete DM3 name

[AlexNi245]

The user has to be able to delete their DM3 name. This requires a button that would trigger the according smart contract call.

• [ ] Add the delete feature for OP names to the UI. Use the mocked function for every contract / backend interaction.
• [ ] Add the according to smart contract call to delete OP names (Alex)
• [ ] Fix the broken endpoint to delete DM3 names (Alex)