For example, i will suppose that in my header is this java code (I can not change it beacause it's located in my header):
How i can block this?
I have this JAVA-library that work on my forum : jquery-latest.jq hoq i can stop it ?
OBs: I can not access my header!!!
The only way that I can think of that will work is to run the page through a 'screen-scraper' and kill the code you don't want with PHP or some other server side programming language.
You can also try to identify the code you don't like and comment it out...
In any event, it is far better to pay for hosting that lets you do what you like than to violate some free hosts TOS to hack their safeguards. If you get caught, than you will likely have your site removed for TOS violation, so better off to play fair.