I doesn't matter what folder the game is installed in. If your trying to run 64bit BF4 then just use the BF4.exe instead of the BF4_x86.exe.
I believe the default shortcut after installation is for the BF4_x86.exe. The files are in the same install folder, so just make a shortcut to the desktop for the BF4.exe to run the game in 64bit.
Hope this helps.