To lock a user out of their system remotely, use the following commands via your RMM.

reg delete HKEY_LOCAL_MACHINE\SECURITY\CACHE /va /f
manage-bde -forcerecovery C:
shutdown -r -t 0 -f

Command 1: Remove cached domain credentials from the registry
Command 2: Force Bitlocker recovery on reboot (recovery key entry screen)
Command 3: Force restart immediately