As john said…
You cannot change the Templates folder location for the newer versions of SketchUp.
It is set to be in your User’s AppData tree - like the default User’s Plugins folder.
It displays in the Preferences dialog, but it cannot be changed.
Maybe, if you close SketchUp and do a Repair [rather than a full re-install] it will jog the path your new user-name.
Although, if you have just renamed your former user account, rather than created a new user account, I think that on Windows the renamed account is remembered by its original name deep inside the system, although it might display to you with its new name, therefore perhaps part of the SketchUp code is reading the base account name, and not your latest change to it ?