Remove useless style files.
Remove useless style files.

oomusou/hexo-theme-openmind,yieme/hexo-theme-freewill,JoshuaZe/freemind,leesei/hexo-theme-freemind,chenzaichun/hexo-theme-freemind,wzpan/hexo-theme-freemind,wzpan/hexo-theme-freemind,blackshow/hexo-theme-freemind.386,leesei/hexo-theme-freemind,zhi1ong/hexo-theme-freemind