Sure there is. If you're at the www.galciv2.com page and have logged in there are three buttons at the top. These are My Posts, Watch List and My Account.
Press the My Account button and from there you can do a bunch of things like edit your character or empire. There are also tabs to Update Images and Personal Information.
If you click on the personal information tab, you'll need to enter your email and password and then you get to a screen where you can change your nickname, change your password and other options.
