You can't. Once a recipient has signed and clicks FINISH it's permanent. If the envelope is not yet complete, you could void it and start again with a new envelope.

Thank you for your reply! How do i void it? The sender has to send me a new envelope? ​

Sorry, I didn't realize you were the signer, not the sender. If you've already signed and clicked FINISH then you don't have any further action available. Only the sender of the envelope can void it if it isn't yet completed by all signers.

You could ask the sender to send a new envelope. But the signer cannot submit without signing every place required. If the sender creates a new envelope and places the same required signatures, your only choice is to sign where they designate OR decline to sign which also voids the document.