The forward was left out of the Red Devils' squad for the third game in a row for their clash with Bournemouth at Old Trafford.
Despite that, Rashford was in attendance at Old Trafford for the contest.
It comes after Rashford's bombshell interview in which he revealed his desire for a 'new challenge' away from the club.
Having progressed through the academy setup, the 27-year-old knows the club better than most but according to Man United legend Neville, it's time that Amorim takes control of the situation.
Speaking to Sky Sports, Neville said: "Something has to change at Manchester United.
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For 10 years there's been a lot of the same players delivering the same results."We've talked about culture a number of times. If there's players who aren't quite fitting in, for one reason for another, if they've not got good enough quality, they've got to be let go."Ruben Amorim knows now, five managers before him have fallen.
"Some of those have shown faith in these same players.
"It's a case of protecting himself and doing the right thing for himself and the club."
Rashford signalled his intention to leave the club earlier this week in an interview with Henry Winter.
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Rashford said: "For me, personally, I think I'm ready for a new challenge and the next steps.
"When I leave it's going to be 'no hard feelings'. You're not going to have any negative comments from me about Manchester United. That's me as a person.
"If I know that a situation is already bad I'm not going to make it worse. I've seen how other players have left in the past and I don't want to be that person.
"When I leave I'll make a statement and it will be from me. 100 per cent."
Rashford added: "I'm halfway through my career. I don't expect my peak to be now.
"I've had nine years so far in the Premier League and that's taught me a lot, that's helped me grow as a player and as a person.
"So I don't have any regrets from the last nine years.
"I won't have any regrets going forward because I take things day by day and sometimes bad things happen, sometimes good things happen. I just try and keep a fine balance."