LACIE external drive out of storage

My LACIE external drive has been running low on storage so I went and deleted a lot of what was stored on this external hard drive so that I can free up some space. I made sure it was fully deleted by emptying the trash can and no matter how much I remove from the external drive, it still says that it is almost out of storage. With the amount that I've already deleted, I should have a lot more space by now. I don't know what else to do. Are there more files stored somewhere else that I need to delete?? Please help! Final cut is not letting me save anything to this drive because it says it has almost has no storage, even though I deleted mostly everything.