After using WHM, I created a new account for a website but when I enter the public_html, I see a cgi-bin folder, I do't know why it was there and it use for what? Should I delete it my public_html? if deleted, I can re-create it without any issues?
Yes, you can delete if you don't have CGI scripts to run from your application [ which you normally put into the cgi-bin directory and execute ]. Later you can recreate the directory anytime without any issues.
The cgi-bin directory seems to be a relic of a long ago era.
Before mod_cgi was created and commonly used in Apache, the cgi-bin directory was necessary to execute CGI based scripts.
But now with mod_cgi and the cgi-script handler, any file with a .pl or .cgi (common CGI file extensions, others can be defined) can be executed in any directory (assuming ExecCGI is enabled, which is also common).
You could effectively remove the treatment of the cgi-bin as a ScriptAlias directory and just leave it as a normal directory as long as you have mod_cgi with the cgi-script handler and ExecCGI enabled.
But this also leads to a bigger question. How many people actually still use CGI scripts? Most everything is PHP nowadays.