https://deadline.com/2021/10/walker-lindsey-morgan-exit-micki-ramirez-season-2-cw-series-1234865144/

Morgan cited "personal reasons" for deciding to leave her role as Micki Ramirez, the Texas Rangers partner of Jared Padalecki's Cordell Walker. A date for her final appearance has yet to be determined. Walker returned for Season 2 last night. Morgan could potentially return as a guest-star in the future. “After much thoughtful consideration and introspection, I have made the incredibly difficult decision to step away from my role as Micki Ramirez on Walker for personal reasons, and I am eternally grateful to have the support of the producers, CBS Studios and The CW in allowing me to do so,” Morgan, a veteran of The CW's The 100, said in a statement. “The opportunity to play Micki has truly been a blessing as has working alongside the incredible cast and crew of this terrific series. Please know that I will continue to root for my TV family and wish them all the best.”

How will Walker move forward following the departure of Lindsey Morgan's Micki? (https://ew.com/tv/walker-anna-fricke-season-2-without-micki)

"He's definitely lost. He's feeling the lack of Micki," showrunner Anna Fricke says of tonight's return one month after Micki's goodbye. Fricke adds that "she is the one who really pulled him out of the darkness and set him on the road to reform. Also, not only reform as a ranger, but she also was the voice in his head that was like, 'Hey, pay attention to your kids. Go home, be a good person.' She was the angel on his shoulder."