HOW TO REMOVE THE PART IN SOLID WORKS?
I hope this helps and is what you were looking for.
I re-drew it as it was hard to just fix your current model. I used the shell feature after making the two tubes with the fillets and without the end flanges. I have provided the file as well as a screen shot of the model with the feature tree. let me know if you need more step-by-step pictures or a video.