It is possible to refuse to sign a document if you have been assigned to do so but don't want to for various reasons.
To find the e-signature case, click "Documents" and "E-signatures" in the left menu. All documents assigned to sign are under the "Needs my signature" tab. Go to the document you don't want to sign and click the "Sign" button next to your name.
At the bottom of the document, click the "I cannot sign" option.
Select "I don't want to sign the document" in the next step.
Write a comment about why you do not sign the document, and then click the "Reject now" button.
When you have refused the signature, the e-signature case will end up in the "Rejected signatures" tab. If a comment has been left about why the signing has been refused, a "Read more" button will appear showing the comment.