1) If you are brand new to the concept of Bitless Bridles - start here:
If you are saying: What is this? Why would I even think about riding bitless?? Follow this set of links!
Could it be your horse is fine in the bit, but you just want to eliminate that thing in the mouth?
Could it be your horse exhibits signs of bit evasion?
Could it be your horse has teeth, jaw or some other issue and the bit is torture for him/her?
These are some of the reasons people decide to go bitless.