robots.txt not changing

I have made my own robots.txt file and uploaded in the server and is located in the root folder. But when I go to https://uat.deshsanchar.com/robots.txt, it is showing yoast robots.txt file. When I go to tools and file editor, I see :If you had a robots.txt file and it was editable, you could edit it from here.

I gave full permissio to all my files, not working. How can I solve this?

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