Access to my passport 2TB ultra

I made a backup at My Passport couple of months ago. Because I want to change this, I deleted files with finder at MyPassport. When I look at MYPassport there are no files but it says there is only 89 GB space left. Very strange because it should be 2TB. Files are really gone (no problem because I have other backup) but how can I use the full 2TB again?