RE: It's Hive moon time

No, no access to old node needed, you can find cli_wallet here: https://gtg.openhive.network/get/bin/ (just use command provided earlier)
Or you can use transmitter.
I'm not sure which could be easier for you.

Are you on Linux? You can use gtg's binary cli_wallet on Hive with this command:

./cli_wallet -s ws://rpc.ausbit.dev:8090

Set a password with set_password, import your active key with import_key key where key is your private active key, and then enter this command:

update_witness nathanmars "" "STM1111111111111111111111111111111114T1Anm" {"account_creation_fee":"3.000 HIVE","maximum_block_size":65536,"hbd_interest_rate":1000} true

That will disable your witness block scheduling.

This is what I can offer you as far as using local software. See @ausbitbank's comment for an easier way.

If you're not on Linux, and have Windows 10, you can install the Windows Subsystem for Linux with Ubuntu by:

Open Windows PowerShell as administrator (type windows powershell in start menu, right click, Run as administrator.
Enter wsl --install -d Ubuntu
Let it install.
Enter name and new password
Enter wget https://gtg.openhive.network/get/bin/cli_wallet
Then chmod +x cli_wallet to make it executable
Then follow the instructions at the top to connect to ausbitbank's node and do the rest.

Alternatively,
check out https://hive.ausbit.dev/witness , login with keychain in the top right and use that to set your signing key to STM1111111111111111111111111111111114T1Anm
to disable your witness