However, the Waikato MP has been offered a pathway back to the frontbench by leader Chris Luxon despite his conduct.
On Thursday, parliament's privileges committee found Mr van de Molan was aggressive, hostile and unprofessional towards Northcote MP Shannan Halbert during a transport committee hearing.
An independent barrister found Mr van de Molan, frustrated at his lack of questions during the hearing, walked over to him and asked him to "Stand up mate" repeatedly before blocking the exit.
"It was really intimidating at the time," Mr Halbert said.
Parliamentary staff were so uncomfortable they considered the need to ring for security during the 30-second incident.
Mr van de Molan, found in contempt of parliament, is due to speak at parliament later on Thursday.
In a statement, Mr Luxon said Mr van de Molan's behaviour was "not up to the standards I expect of National MPs".
"Tim has had a difficult year personally over the last year, but that does not excuse any MP indulging in the behaviour described in the report," he said.
"Following a discussion with Tim this morning, I have removed all his portfolio responsibilities namely Defence, Veterans, Building and Construction, ACC.
"Everyone makes mistakes, and there is a path back for Tim provided he can demonstrate to me, the wider National caucus, and himself, that he has learnt from this incident and grown as a result."
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