I accidentally uploaded the complete codecanyon-QqZdjyPs-ajax-search-pro-for-wordpress-live-search-plugin file. Now the file is hidden in /? S = the search. How can I completely delete the file from the server?
Do you mean you tried to install it via the plugin manager and it failed? It will not do any harm whatsoever, the plugin manager will simply abort the installation.
WordPress usually stores the uploaded files in the wp-content/{year}/{month}/ directory. The uploaded zip file therefore should be in the wp-content/2021/09/ directory.