If you've already signed the contract, but the other party hasn't yet, you can easily revert your contract to an editable state. To do so, go to your contract and click the More Options dropdown in the corner.
Click "Unsign & Edit" to undo your signature and allow you to make changes once again.
Once you are done with your changes, you can resend it for signature. Please note, however, that previous links will be invalidated for security purposes.