Shaw, 22, has endured a rather disappointing spell since joining the Red Devils from Southampton in the summer of 2014 and looks unlikely to break into Mourinho's first-team set-up at present. The Portuguese has handed Shaw just two substitute appearances this season, both coming in the Carabao Cup.
Mourinho's treatment of Shaw was scrutinised at length last season - the former Chelsea boss publicly criticised the sporadic England international on a number of occasions and banished him from his starting line-up - and Nicol, who played for United's arch rivals Liverpool for 13 years, thinks Shaw must leave the Europa League holders for the good of his career.
"He [Shaw] needs to go, he needs to leave," Nicol said on ESPN, relayed by The Express. "Listen, as soon as your manager is annihilated you in the press the way he got annihilated, you can forget about it. He's a good player but he's wasting his time at Manchester United."
Nicol's fellow pundit Craig Burley echoed his sentiments, and does not see any way back for Shaw at United. The former Chelsea midfielder believes Mourinho's public dressing downs have severely hindered the full-back's chances of succeeding at United and thinks Shaw is understandably suffering from a crisis of confidence.
"He's a good player, he is a good player," Burley said. "Don't forget he had a horrendous leg break, so it isn't easy.
"You don't really want to be thrown under the bus by your manager coming back from that, it doesn't help. It looks as if he's completely lost confidence. Going to such a big club, injuries, manager doesn't like you."
Mourinho afforded Shaw just four minutes of action during United's 2-0 win over Swansea City in the Carabao Cup on Tuesday (24 October) and will almost certainly not include the full-back in his squad for the game against Tottenham on Saturday. Mauricio Pochettino's men were credited with an interest in Shaw a few months ago, while United have been reportedly sniffing around Spurs' Danny Rose, who made his first start for almost nine months in his side's 3-2 loss to West Ham United.