Please tell me this issue.. how to solve this..

Fatal error: Uncaught Error: Call to undefined function osc_is_admin_user_logged_in() in /home/ca****s/public_html/oc-includes/osclass/classes/database/DBConnectionClass.php:177 Stack trace: #0 [internal function]: DBConnectionClass->__destruct() #1 {main} thrown in /home/ca****s/public_html/oc-includes/osclass/classes/database/DBConnectionClass.php on line 177

Please find attachment how to solve those issue? Its showing blank and it cant delete also please help

@ishan
1) osc_is_admin_user_logged_in is core function (hUser.php)
2) This happens when there are foreign keys on t_item table and during removal, everything is deleted, but only record in t_item table and table from foreign key are kept. To fix it, find foreign key and delete it.

from where i need to find foreign_key?? in which files??

@ishan
No file, database.
https://www.w3schools.com/sql/sql_foreignkey.asp