To change the name of ownCloud main folder, there is a little trick you can do on Linux (may work as well on other platforms).
First, close the ownCloud application on your desktop : commonly, right click the systray icon and quit ownCloud. This avoid any conflict when renaming the folder.
Now, you can rename your local folder. For example :
mv ~/owncloud ~/docs
Open your ownCloud configuration file : location depends on the platform (cf ownCloud docs for more infos). On my Linux desktop, I did :
vi ~/.local/share/data/ownCloud/owncloud.cfg
Then, look for a line with “localPath” inside. Someting like :
0\Folders\1\localPath=/home/user/owncloud/
Now, update the folder location to your needs. For example :
0\Folders\1\localPath=/home/user/docs/
Restart your ownCloud app and voilà !