Downgrade one ui 3.1 to 2.5 galaxy s10

[Yasin.mirza]

Hello Experts,
i want to downgrade my galaxy s10 g973f from one ui 3.1 to 2.5.How can i downgrade ? it looks like not possible for me to downgrade .can you help me or share a method.
Baseband version : g973fxxsfue6
kernal 4.14.113 -21644994
knox 3.7