All My Website Pages Title Tags have -logo in Google Search Result

When I searched my website in Google, the title tag of all my web pages ended with strange word “-logo”, see attached screen capture.

I read from this post that https://www.premiumpress.com/forums/topic/google-titles-showing-%E2%80%A2-logo-at-the-end-of-all-posts/, I need to change the class_core.php to get rid of the word “logo” but after I uploaded the revised file, it gave me server error.

Pls advise how else could I remove the word “logo” and not causing problem to my site?

Thank you.