Hi There!
To stop or pause the bitlocker encryption, from an elevated (Run as administrator) powershell or command prompt window, you can use the manage-bde tool.
To get the current status of the drive and the encryption, the command would be manage-bde -status <drive letter>.
Example: manage-bde -status c:
To pause the encryption you can use the command of manage-bde -pause <drive letter>.
To resume the encryption you can use the command of manage-bde -resume <drive letter>.
To turn off bitlocker encryption you can use the command of manage-bde -off <drive letter>.
Hope this helps you!