Looking at your command output
- You are using controlfile
-Your backups are in the server filesystem
It seems like if this bakup isn't cataloged in your controlfile.
You can see which backups are cataloged in your controlfile with rman command
RMAN> LIST BACKUP;
But at the end, if you have your backups in disk, you can simply delete with operating system commands it and resync the contents of the disk with the controlfile with command
RMAN> CROSSCHECK BACKUP;
Rman will loook at your backups and mark like EXPIRED if "Object is not found either in file system (for DISK) or in the media manager (for sbt)."
After this, you just need to delete this backups from controlfile with