Why was brenda kicked off 90210?

Brenda Walsh, played by Shannen Doherty, was written off "Beverly Hills, 90210" after the fourth season primarily due to behind-the-scenes conflicts and controversies surrounding her behavior. Reports indicated that Doherty's on-set difficulties, including clashes with cast members and production staff, contributed to her departure. The show's producers felt it was best to move on, leading to Brenda's character relocating to London.