how to delete a time machine backup file?

Hello. I did a time machine backup at 6 pm today. When I looked in the Finder, in the Time Machine disk, the backup file for 6 pm was not there, so I did another backup at 6:05 pm. When I looked in the Finder, the backup file for 6:05 pm was not there, so I thought this was strange, and did another backup at 6:10 pm, and the backup file was not there. So I ejected the external disk and mounted it again, and now I had the three backups for 6pm, 6:05pm and 6:10 pm. So now I don't want to have so many backups, and I want to delete the ones for 6pm and 6:05pm, and just keep the one for 6:10 pm. Can I delete the two backup files from the Finder? O what do I need to do? Thanks. PD: if I enter Time Machine, there seems to be duplicate entries for these backups. Instead of using the Finder, should I delete both entries for each backup from within Time Machine? I would prefer to use the Finder if possible. PD2: it appears that there is no way to delete a backup from within Time Machine.