nullify
verb
nul·li·fy
| \ ˈnə-lə-ˌfī
\
\
nullified;
nullifying
Definition of nullify
1
: to make null (see null entry 1 sense 1)
especially
: to make legally null and void
nullify a law
2
: to make of no value or consequence (see consequence sense 3)
a promise later nullified