How to remove a folder in the VMware datastore

HI,

First VM4&VM5 is migrated while migration of VM20 is running, so migration of VM4&VM5 failed several minutes later. But VM4  folder could be seen under backup2 datastore. When VM4  is migrated again after migration of VM20  finished, VM4_1 folder can be seen in datastore backup2.  And VM4 folder includes a DB_backup-flat.vmdk file.

So I have some questions:

1) How can I remove the VM4 because it is useless?  Should I delete  DB_backup-flat.vmdk file and then delete VM4 folder? But I cannot find steps to delete VM4 folder in the backup2 datastore. Who Can provide the steps ?

2) How can I rename VM4_1 folder name to VM4?

Thanks!