In an official statement, The Flash showrunner Eric Wallace has explained why Hartley Sawyer was fired. Sawyer joined The Flash in season 4 as the former police officer-turned private investigator Ralph Dibny. The character evolved into his comic book superhero persona, the Elongated Man, over the course of the season and has been a recurring player on The CW's TV show ever since. That will no longer be the case when The Flash returns for season 7, after Sawyer was officially fired from the series.
The announcement was made in response to Sawyer's older racist and misogynistic tweets resurfacing online and has been confirmed via a joint statement issued by Warner Bros. TV, Berlanti Productions, and Wallace (who took over as The Flash's showrunner in season 6 after serving as a writer and producer in earlier seasons). Wallace has since released an additional statement online that covers his own personal response to reading Sawyer's Twitter posts and the reasoning behind his firing.
In addition to explaining the situation with Sawyer, Wallace affirmed his commitment to hiring more "Black and Brown writers, directors, actors and producers of all genders to help tell FLASH stories", and voiced his support for the Black Lives Matter movement. You can read his entire post (which he tweeted out), below.
On top of being The Flash's first Black showrunner, Wallace has already been lauded for the way he's allowed the show's non-white characters (especially, the women of color) to shine since he took over. Season 6 not only brought Candice Patton's Iris West and her skills as a journalist to the forefront, it gave her an investigative team of her own, composed of Allegra Garcia and Kamilla Hwang (with Cecile Horton often aiding them in their investigations). This was all the more significant in light of Patton's experiences in the past. When she joined the show as Barry Allen's classic love interest (a character typically portrayed as white in the DC Comics universe before then), Patton had to deal with a lot of racist attacks from fans online in response to her casting. So, her getting to play a more active role in season 6 was not only a long overdue development, but a welcome move on Wallace's part - one that suggests he will follow through on his commitment to hiring more Black and Brown creatives to work on the series moving forward.
As for Sawyer, he's the second actor to leave the Arrowverse recently, following Ruby Rose stepping down as Kate Kane on Batwoman. In that case, she was not fired but left after (reportedly) on-set tensions led to her and Batwoman's producers agreeing to a mutual break-up, so to speak. Showrunner Caroline Dries has since confirmed Batwoman season 2 will replace Kate with a brand-new character, rather than recasting the role. That seems unlikely to happen with The Flash, what with Ralph still being a central part of Team Flash heading into season 7, so the odds are more in favor of Mr. Dibney either being recast or written off the show. Even in the latter case, Team Flash won't be hurting for members in season 7 thanks to recent additions like Chester P. Runk (a nerdy Black scientist who joined the series in season 6).
The Flash season 7 is expected to premiere on The CW in early 2021.
Source: Eric Wallace/Twitter