Yes, insoles are removable on most TRUEs, including All Day, Original and Lux models. There could be a dot of glue keeping it in place but you can easily pull out the insole. You can replace or add your own orthotics/inserts or simply refresh your TRUEs by replacing your insoles with a fresh TRUE set to give your shoes new feel. 

Men's 5mm comfort replacement insole - works for All Day, Original or Lux models

Women's 5mm comfort replacement insole - works for All Day models

The only exceptions to the above, are the Future Staples models, as they feature special, super cushioned insoles, so as this platform has unique construction, we do not recommend removing to replace this insole with your own.