Hello,
Thank you for contacting us and bringing your concern to our attention.
Please head over to your WP Dashboard > Rank Math > Titles & Meta > Posts and from there, remove the %sitename%
variable in the Single Post Title field.

Hope that helps and please don’t hesitate to let us know if you have any other questions.
I have already remove %sitename% from single post and also Edit all Snippets in all blog post Section but still search appearance is adding site name at the end of the post title
Hello,
Can you please share some blog post URLs with us so that we can check them further for you?
However, please note that the title in the screenshot you’ve shared is just for example and it is static. It just shows how the separator will look on your title.
We are looking forward to helping you.
Thank you.
Hello,
The correct title is already generated by Rank Math as you can see from the screenshot here:

In this case, Google still hasn’t seen he changes you made. Please give it some time for Google to recrawl those URLs and the details on the SERP will be updated.
Don’t hesitate to get in touch with us if you have any other questions.
Yes I think It Means I don’t have to do anything With it It is the Problem from Google….
Hello,
We are glad to know that this issue has been resolved. Thank you for letting us know.
This ticket will be closed now, but you can always open a new one if you have any other questions or concerns. We are here to help you with anything related to Rank Math.
We appreciate your patience and cooperation throughout this process.
Thank you for choosing Rank Math.