Regular expressions allow you to filter out files and folders from your sitemap
by looking for string patterns.
You should enter one regular expression per line in the configuration wizard.
The below external websites cover the subject in more detail :
An example of excluding a particular file or folder where the path begins with
the pattern :
^\MyFolder\*
Excludes
\MyFolder\Anything.html
Does not exclude
\Test\MyFolder\Anything.html
Excludes any full file path where it ends in index.* :
*\index.*$
excludes
\MyFolder\index.html
\MyFolder\index.gif