Time Machine does its own management of storage space, deleting older backups to make room for the most recent ones as required. Drag to trash is NOT recommended on a Time Machine backup!
Now that it's been done, try holding the Option key down while emptying the trash.
This is probably the best resource for Time Machine info:
I've only just got round to looking at this again. I'm afraid I'm not tech savvy enough to follow the pondini instructions, as clear as they might appear. I'd need a step by step guide to do what it looks as though I'll have to do on this. My Time Capsule doesnt seem to be deleting old backups either.
I can't possibly make it more clear than Pondini. Sorry. I use his site faithfully whenever I have a question about Time Machine. Why is it thatyou feel you need to manually delete backups? Time machine doesn't do a full backup everytime it runs, it just backs up files that were changed since the last backup.