You should be using webread rather than urlread as stated in the documentation. You can use regexp to extract HTML elements from a HTML document. There are examples on how to do so on the regexp documentation page.
Use the following code to extract < table > elements.
ur = 'https://www.w3schools.com/html/html_tables.asp';
str = webread(ur);
%Using urlread instead will give the same output.
%str = urlread(ur);
expression = '<(table).*?</\1>';
matches = regexp(str,expression,'match');
matches contains the two < table > elements in the HTML.
