remove webbrowser lines

hi
i need a code for deleting any lines of webbrowser
i need have a limite for my webbrowser
this means i need code for i have webbrowser by only 2000 line
if my webbrowser lines are 2001
auto remove first line of webbrowser

i need a limiter for my webbrowser
can anyone help me please ?!


Thanks in advanced
sorry for my bad english