Disinherit or renounce (6)
I believe the answer is:
disown
I believe this is a double definition.
'disinherit' is the first definition.
(synonyms)
'renounce' is the second definition.
(I've seen this before)
(Other definitions for disown that I've seen before include "Disclaim or deny" , "Repudiate - disinherit" , "Repudiate, cast off" , "Repudiate, disclaim" , "Reject all connection or relationship with" .)