How to remove unwanted faces from 3D Solids?

[iamerg]

I have been using Sculp & Patch tool to form the bottom but results to the same issue shown on the image. How do I remove it?

 

[shift1313]

is the bottom supposed to be flat/planar? Is there a boundary fill there? That generally happens when its trying to meet a Tangency constraint and the geometry won't quite let it happen. Probably have to delete the bottom faces, extend the side faces and then trim them with an extruded face that is planar and a single body. hard to say just from the picture but thats my guess.