to give up your claim to something by writing your name on a document sign over somethingHe tricked her into signing away the property that she intended to leave to her friend.You're signing your rights away when you sign that form.
Usage notes: sometimes used in the form sign your life away(give up all your rights): It felt like we had to sign our lives away to get a loan from the bank.
To give something up by signing one's name; relinquish something by signature: When they agreed to settle the lawsuit, they signed away their claim to the estate. If you wanted the right to sell your work independently, you shouldn't have signed it away by joining the organization.