You can escape it using backslash character. Replace <% with <\%. Following example showcases the same.
<html> <head> <title>A Comment Test</title> </head> <body> <h2>Syntax: <\%= (new java.util.Date()).toLocaleString() %\></h2> <p>Today's date: <%= (new java.util.Date()).toLocaleString()%></p> </body> </html>