can I remove cache feature from Squid or how can I make the time of cache is very short

Hi

Please help me to understand the question described as below:

I added a service in c-icap to block some URLs(for example, www.yahoo.com)  and I did it. It displays permission denied web page (designed by me) when the user enters these URLs.

After I made www.yahoo.com available, it does not display real www.yahoo.com web page. Instead, it  displays permission denied web page when I enter www.yahoo.com. It keeps displaying  permission denied web page until several minutes are passed.  

Is it cache feature from Squid? Can I remove cache feature from Squid or make the time of cache is very short. I hope after I made www.yahoo.com available, I can see real www.yahoo.com web page in short time and I do not want to see permission denied web page for several minutes.

Thank you in advance.
Forrest