Spending three years at the St James’ Park, Benitez refused to remain with the club, insisting the club’s hierarchy share not the same vision with him.
And having seen out his contract at the end of last season, the Spanish trainer, who refused to renew his contract joined Chinese Super League club Dalian Yifang on a two-and-half-year deal.
With the Magpies faithful always recalling the former Real Madrid manager’s moments, 21-year-old Longstaff wants the fans to forget about the 59-year-old tactician and begin to rally support behind newly-appointed Steve Bruce.
"I was speaking to Rafa throughout the summer and ultimately I think everyone wanted him to stay," Longstaff told Sky Sports.
"But that's football. Things change and ultimately he didn't want to stay.
"It's in the past now and I think everybody, as harsh as it sounds, has to sort of forget about him, as tough as that can be.
"We've spent a lot of the start of the season talking about Rafa and he's not here.
"Ultimately he doesn't have an impact on the team or football club at this time.
"If the team start picking up results, everything will look more positive and people will forget about the previous manager, as long as we're successful on the pitch."
Newcastle have lost all their first two games of the season, but looks to a get win over Mauricio Pochettino’s side on Sunday at the Tottenham Hotspur Stadium.
