Clearsnapshot Error "The process cannot access the file because it is is being used by another process"

Hi,
i want to manage backups or my cassandra node, and i need to copy snapshots to a remote path, and then, clean these snapshots.
Trying to delete folders manually, or using the nodetool clearsnapshot, i am having errors because i have files in use so i can't clean them.
Of course if i stop the Cassandra node, i can do it, but it is something i want to avoid.
Clearsnapshot error say me that these files are blocked in the following path: "data\system\compaction_history\"
Why are these files locked?
Regards,
Raul