Depends on the scratch....
All scratch removal is by polishing, which in turn involves surface reduction. Titanium is notoriously difficult to polish, since the surface is almost always matte.
Most people say leave the scratch --it adds character and some small ones are inevitable. But it if bothers you, at your own risk try using an ink eraser. Make small, consistent rubs all in the same direction. That sometimes works, or at least works well enough.
If it's more serious, then I understand that IWC can "refinish" a tintanium case,presumably by sand-blasting. I assume that could be done on a bracelet, but it is neither inexpensive nor quick (it must go to the factory(l You may be able to get a part replaced through a dealer, and that might be less costly.
Good luck,
Michael