I assume that the permissions of the file have been set to read-only for the group psacln and anonymous users. It's probably a file that was created by a script, so it is owned by the webspace system user arabh1x. The screenshot does not show the file and its owner, group and permissions, but it is likely the cause. Could you please check that?
In that case the easiest solution is to login as "admin" or to login through SSH to your Linux shell, either chrooted or root does not matter in this case. From there you can use the Linux "rm" command to remove the file.
Should that not be a possible approach for you, you can also try to edit the file permissions and change them to at least 664 (write and read permissions for the group psacln), afterwards you will be able to delete the file through file manager, too.
Should that not be possible either, you can use this PHP script to remove the file. Simply create a file ending on .php and upload it into your webspace:
PHP:
<?php
unlink('/var/www/vhosts/arabcomics.net/httpdocs/wp-content/plugins/xemi.php');
?>
Then open the file in a browser once.
Please also consider that the file is located in the Wordpress plugins directory, so it might be part of a plugin. The plugin may not function properly any longer after it was removed. Maybe it is best to remove the plugin instead of only removing the single file.