I'm not sure which of the following scenarios you mean:
a) you have a currently running Gold or Silver subscription and want to stop that immediately and want your money back for the remainder of the time you paid for. If that's the case, I'll forward you to the developer, or
b) you have a currently running Gold or Silver subscription and don't want to prolong it after the time it runs out. In that case you need to do nothing, the subscriptions aren't self renewing, or
c) something else I didn't think of.
Please tell me which version it is, and if c), explain a bit more.