Britney Spears' MTV performance caused a stir
Los Angeles-based The Firm said: "We have terminated our professional relationship with Britney Spears.
"We believe she is enormously talented, but current circumstances have prevented us from properly doing our job," the statement continued.
Spears hired the company for the run-up to her comeback album, which is due out in the US on 13 November.
Sacked
Meanwhile, Spears has parted company with her lawyer in an ongoing child custody battle with ex-husband Kevin Federline.
Laura Wasser, who represented the singer until Monday, said she would be in "excellent hands" with her new legal representatives.
No reason was given for the change.
A former bodyguard for the star, who was due to support claims of erratic behaviour in the case, failed to testify at the hearing in Los Angeles.
Tony Barretto was called a 'key witness' by his lawyer
Tony Barretto arrived in court but was unable to give evidence before lawyers held debates in a closed session.
His lawyer Gloria Allred said: "Our client was prepared to testify on issues of nudity by Ms Spears, drug use and safety issues involving the children."
Mr Barretto was hired by Spears in March after she left a rehabilitation facility, but was sacked two months later.
According to Ms Allred, he lost his job because "he didn't hear her when she asked him to pick up her hat".
Spears' former lawyer Ms Wasser commented that Mr Barretto was a disgruntled employee.
The singer, whose divorce with Federline was finalised in July, currently has joint custody of their two sons Sean Preston and Jayden James.
''The Firm'', a company which pop singer Britney Spears hired to manage her career just over one month ago, no longer wishes to  manage Spears, and has terminated the services they were providing her to promote her new record.

"We have terminated our professional relationship with Britney Spears. We believe she is enormously talented, but current circumstances have prevented us from properly doing our job," said the company in a statement to the media. Jeff Kwatinetz was the manager for Spears. It is not yet known what circumstances caused the company to sever their ties with Spears.

Spears is releasing a new album, scheduled to be put on shelves in November, and her record label, , has stated that the recent incident will not delay the release of her record.

"The label does not comment on artist/management relations. We're gearing up for a Nov. 13 album release date," said the record label in a statement to the media.