Remove delegate API client shouldn't sign the message

[moisses89]

What is needed?

The function remove_delegate of transaction service api is signing the message with wallet provided by parameter, but this signature should happens outside of the remove_delegate function to let other types of wallets as hardware wallets sign the message. I'd suggest that remove_delegate should just receive the message_hash and the signature.

[Uxio0]

Makes total sense @moisses89 , good call