disaffirm
/ˌdɪsəˈfɜrm/; /ˌdɪsˈæfɜrm/Definitions
1. verb
to refuse to confirm or affirm, or to declare to be invalid
“The judge disaffirmed the verdict after discovering new evidence.”
2. noun
the act of refusing to confirm or affirm, or the declaration that something is invalid
“The disaffirmation of the contract was a major setback for the company.”