The VM has a snapshot named "Created by vRanger (do NOT modify or delete!)". As long as there is no active backup/restore/replication job running against this VM at the moment, It safe to delete such snapshot?
Occasionally, due to connectivity issues, or if vRanger machine was powered off when vRanger was running jobs, the virtual machines may have old open snapshots, that were created by vRanger.
Old vRanger snapshots can be safely deleted if vRanger currently is not running any job against the VM in question. Also if you do not delete snapshot manually, on next backup vRanger will check for any, vRanger, open snapshots and close them before proceeding with normal backup/restore/replication process.
Note: The snapshot description has a timestamp, which may be used to determine when and by what vRanger instance it was created