You need to modify the backup policies and change the retention period for the VMs managed by the backup policy in order to clear up old restore points. If for example your backup policies are set for 0 day retention, this means you are keeping the data indefinitely.
If you happen to see a restore point outside of the retention period set by a backup policy, you can manually delete the data by mounting a UNC path the to target storage that vmPro points to and then simply deleting folders that are outside of the retention period.
If you are using NFS between the vmPRO and your storage device (for example DXi) then another convenient way to remove older recover points is mount the storage location from ESX and then use the Datastore Browser: