Delted "Space" Time Machine Backup This could sound like a really dumb question as I don't even know what I did wrong.  Please help!

I have had this LaCie backup (500 GB) for years since my friend suggested few years ago.  I have been pluging it in my mac every few months and just let it do its thing.  Luckily, I never have to retrieve any info from it.

Recently, I started using some Adobe software and now have a lot of large files in my lapto.  When I tried to back up today, I thought to myself: "I do not need all the old backups, maybe I'll just delete it all and start fresh!"

So I plugged in the time machine and just grabbed the whole folder that labeled as my mac's backup to the trash.  Without much thinking, I typed my password when a window popped and ask for administrator's password.

But now I can't backup my laptop as it says I have only 150 GB available and my it needs 300 some to backup.  Is it possible that I "accidentally" deleted my 300 some GB space from my LaCie??  I went to the trash folder trying to find "what exactly" I deleted but can't find anything and am very confused.  Please help?

Thank you very much.
Elsie
It could be that there are some files left on the time machine drive.  Try emptying the trash.  IF that doesnt work you can run Disk Utility in the Utilities folderin Applications.  Select the disk you want and partition it.  Then you should be able to do a full time machine backup.  Once that operation has completed select that drive as your time machine drive again.