Ms English said the job "became increasingly untenable to continue. As time progressed I continued to be marginalised.
She said she phoned Lord Sugar in May 2011 and asked if she could meet him but claims "he made it abundantly clear that he didn't want to see me."
She said she told Lord Sugar: "I have tried so hard for so long and it's not working. I'm an overpaid lackey at Viglen. My pride would not allow me to continue doing it."
Ms English said Lord Sugar then offered her a role in another company which she started in June 2011.
She said Lord Sugar told her that he had given her the second role because he did not want to damage the integrity of The Apprentice or the BBC, or to arm his own public image.
The tribunal continues.
Ms English, of Whitstable, said she was not taken seriously by her colleagues, while she did not feel like Lord Sugar's "apprentice" as she said she only saw him five times during her 13-month employment.
She said: "I was provided with a desk and a phone but that was pretty much it."
Ms English fought back tears as she said she was given no guidance about what she was meant to be doing, and was "ostracised" by her colleagues who told her she had taken over another women's job.
Relegated to carrying out basic administrative tasks, Ms English said her employment was a "sham".
She added: "The career-enhancing opportunities that The Apprentice position had been sold as simply failed to materialise."
A winner of TV show The Apprentice, from Kent, described the £100,000-a-year job she was given by Lord Sugar as that of an "overpaid lackey", an employment tribunal has heard.
Stella English beat 15 other wannabe apprentices to win series six of the hit BBC1 show in 2010.
She was given a role in Lord Sugar's Viglen division, supplying IT equipment to academy schools, but she said that when the business mogul told her he would not be renewing her contract she was given no choice but to resign.
She is claiming constructive dismissal against Lord Sugar, who attended the hearing at East London Employment Tribunal Service.