sdo provides a single command to set active identity of a validator to unstaked one.

 sdo validator set-unstaked

It will ask for the network and public key of the validator.

? What is the validator network? (Use arrow keys)
❯ testnet
  mainnet
✔ What is the validator network? testnet

Once chosen the network, sdo will ask for pubkey of the validator

? What is the public key of active validator?
✔ What is the public key of active validator? 32nTAQSAxzSbvURguFvfz5FX1g4enbvgyttMYHr1KJqM

sdo will take care of the rest.