How can I empty my trash without typing in my password?

Recently every time I try deleting an UNLOCKED Word document, Excel spreadsheet, PDF, file folder etc. I am asked for my account name and password. Previously, all I had to do was drag the item I wanted to delete into my trash bin, and it would disappear. How can I restore my Macbook Pro so I don't have to enter a password each time I delete an item from my computer? I am running OSX, version 10.8.2.