You can't. You can create a new user account with the name the way you want
it to appear in the folder name, then copy the Owner account to the new
profile.
Copy a User Profile:
Open System in Control Panel. On the User Profiles tab, and under Profiles
stored on this computer, click the user profile you want to copy, and then
click Copy To.
In the Copy To dialog box, under Copy profile to, type the location for the
new profile, or click Browse to select the path.
Click Change to open the Choose User dialog box, click a new user from the
Names list, and then click Add. The new user name will appear in Add Name.
Click OK to add the user as a new user profile on your computer.
Note: You must be logged on as an administrator to the local computer to
copy user profiles. To open a Control Panel item, click Start, point to
Settings, click Control Panel, and then double-click the appropriate icon.
http://support.microsoft.com/default.aspx?scid=kb;en-us;811151
How to Copy User Data to a New User Profile
