As commented above, https://tezos.gitlab.io/introduction/test_networks.html lists the current networks: mainnet, Edo2Net (mainnet test), Florencenet (next protocol, if it passes)
Every network is public and both test networks have free tokens from the faucet. You can participate by downloading/running the latest tezos software and using the --network flag to ...
I was having the same problem, trying to empty an address that was delegated. The error was:
Emptying an implicit delegated account is not allowed.
Although not ideal, a quick workaround was to leave some dust (0.01 XTZ) behind in the address.