Windows Media Player runs in 32-bit version from Program Files (x86) and 64-bit from the Program Files directory.
64-bit Windows 7 includes both 32-bit (x86) and 64-bit (x64) versions of Windows Media Player 12 (WMP12). However, to provide maximum compatibility with existing applications and codecs, 32-bit version of Windows Media Player has been made the default media
Using 64-bit software allows application to run natively and take architecture advantage in 64-bit operating system, and potentially run faster by working with larger data sets at any time. One practical consideration is for users who use Windows Media Center,
which is a 64-bit application.
This is the reason why Windows Media Player is present in both 64-bit and 32-bit directories.
So, it is highly recommended not to delete it from Program Files (x86).
Also, refer the link below for more details on 32-bit and 64-bit Windows: