How do I take over an inactive fanclub?

You can't "take over" a club. clubes aren't owned por the person who started them - they're owned por every member. However, you can still get the ícone and banner changed. The method is different depending on whether the club has 10 or mais members.

The first thing you'd need to do is start a fórum thread in the club asking people to suggest new ícones and banners. Leave that running for about a mês or two. Then,if the club has less than 10 members, you make 2 pesquisas asking members to vote on their favourite ícones and banners, then message one of the F4 asking them to change the club's appearance to the winners. If the club has mais members, you need to use the buttons on the topo, início right of the club's main page which say "suggest a new banner/icon". These make pesquisas which cost members 5 golds to vote (to discourage uninterested people from spam-voting) and the ícone and banner get automatically changed to whichever win these polls.