Bitcoins are redeemable. I just redeemed some bitcoins for plane tickets.
That's trading not redeeming. The later is when the issuer of an instrument withdraws it out of circulation and pay redemption value in the process. Watch the video.
I have news for you. Dollars or your <X> fiat currency are not taken out of circulation either when you spent them (although they can be manually destroyed, just as amounts of cryptocurrency can be "burned" including Bitcoins if devs wanted to do that).
The video explains in detail how dollars are redeemable, taken out of circulation and destroyed (if digital) with every loan repayment.