The outspoken 'Talk' star insists the 19-year-old singer needs reprimanding for his recent behaviour - which has included being arrested for driving under the influence (DUI), driving with a suspended license and resisting arrest, and allegedly being abusive to flight staff who asked him to stop smoking marijuana - and says his conduct can't be excused because his music isn't very good either.
She said: ''[If I managed him] he would have to go to a hospital to get my foot out of his ass.
''And after they pried my foot from his ass, it's all about the music. If you make great music, I'll accept anything. If you're a great artist, I'm not so judgmental. But when you do floppy, poppy, disposable music, I don't care.
''For me, he doesn't do anything that's going to stand the test of time.''
Sharon - who has managed several musicians, including her husband Ozzy Osbourne - says her main priority if she looked after the 'Believe' star's career would be to get him to work harder on his music.
Speaking on 'Chelsea Lately', she said: ''If I seriously managed him, I would put him in the studio until he came out with a great album and then, it gives you a license to misbehave.''
And the 61-year-old star also admitted she refuses to sit in on interviews on 'The Talk' if she isn't a fan of the guest.
She said: ''If it's something I really have a thing against. I'll ask to be removed from the segment.''
The singer introduced "the next generation" in Iceland.
Jack Antonoff hears a ''female voice'' in his head when he writes music.
The show will be seen by everybody at the same time.
The Scottish comedian has been speaking about gaining a knighthood in the Queen's Birthday Honours List.