how to remove a file and change dns server

[Long Wind <longwind2@yahoo.com>]

-rw-r--r-- 1 root root 51 May 15 20:52 /etc/resolv.conf

i can't remove file above, the story behind it:

dns servers are usually provided by isp

but they can't be used with vpn

so vpn provider told me to make a special resolv.conf

which contains dns servers not provided isp

dns server by vpn provider is useful when i visit blocked sites

but they are not as fast as those by isp

my question is  how to change dns server as needed?

it seem that resolv.conf is automatically managed

and how to remove the special resolv.conf