Are you asking how to remove the Volume letter (in this case F
from the MSR partition rather than the partition itself?
It shouldn't have a drive letter assigned to it, and AFAIK, you can go to Disk Managemet, right click on it, choose "Add or change drive letter" and choose remove. It stores the BootMgr, BCD, and Bitlocker info, and doesn't need to be visible in Windows Explorer.