She claims that she was the one who was more or less directly responsible (https://www.quora.com/Why-was-Shannen-Doherty-fired-from-90210/answer/Aly-Wick) as went to her father, Aaron Spelling, who was also the executive producer. And yet, Tori also claims that she and Shannen never had any issues with each other. It was Jennie Garth who Shannen was clashing with.

http://www.agcwebpages.com/BLINDITEMS/2019/APRIL.html

346. ENTERTAINMENT LAWYER 04/27 **#7** (https://www.crazydaysandnights.net/2019/04/blind-item-7_27.html)

It turns out this former A- list mostly television actress had all the power. The actress, who had a couple of hit shows, but nothing for quite some time was added to the new reboot of one of the hits much to the chagrin of the two people who proposed the idea. They couldn't get a greenlight without our actress though. Shannen Doherty/Tori Spelling & Jennie Garth ("Beverly Hills, 90210") (Shannen Doherty Joins ‘Beverly Hills, 90210’ Miniseries Reboot) (A '90210' Reboot With Tori Spelling & Jennie Garth Is Coming & We're Not Worthy)