How to use htaccess to change site.com/directory/ to site.com/ ?

If you only want http://kingphp.com/money directory become http://kingphp.com, use:RewriteRule ^catalog/$ / [L]

If you want all directories become http://kingphp.com, use:
RewriteEngine On
RewriteBase /

RewriteRule ^([^/]+)$ /catalog/$1 [L]
RewriteRule ^$ /catalog/ [L]

Note:If you have other subfolders in there (in that catalog dir, you’ll need some additional rule for that also. This will rewrite your files from catalog/ subfolder to your main url.

How to use mod rewrite forward to a new domain?

For examples, when we visit www.google.com, we want it redirect to http://kingphp.com, we can use the following code:
Options +FollowSymLinks
RewriteEngine on
RewriteRule (.*) http://www.newdomain.com/$1 [R=301,L]

The code posted above should be used on the old server.

How to redirect folders (and all the link)

For example, if we want to redirct http://kingphp.com/php/ to http://kingphp.com/wordpress/

We could use mod_rewrite. Put this in your .htaccess file

Options +FollowSymLinks
RewriteEngine On
RewriteRule /php/(\w+).html /wordpress/$1.html [R=301,L]