There's two answers: what you can do, and what you should do.
You CAN ask to have the logo and banner changed to any club at any time, regardless of activity, and the staff may oblige you. This is considered troll behavior pretty much universally, however.
This has been discussed a fair amount in
link. It's not universal, but the general feeling is that you SHOULD do something like this:
1. You make the icon and/or banner.
2. You post it in the image section.
3. You start a message thread in the forum, for discussing the change. In that forum thread, you also point to #4 & #5, below.
4. You post a pick with an end date, asking users to vote to keep the original icon or to change to the new one.
5. You post a pick with an end date, asking users to vote to keep the original banner or to change to the new one.
Note: the end date should be long enough to allow for enough fans to respond, but not ongoing. 2-4 weeks is probably good.
6. If the users vote to make a change to the icon and/or banner, send a message to the staff (using the "contact us" feature) with:
a) the name of the club
b) the URL(s) of the completed picks, showing that users wanted the change
c) the URL of the new icon
d) the URL of the new banner
7) The staff makes the change.