Welding in Abaqus to generate 3D tubular frame

I want to design one 3D frame by using tubular members . When I am using the cut/merge option, some part remains inside the tubes, and I am not able to remove them manually by using the delete command—Is there any other way to do this . Please help me out.

Edu ​​​​​​​Abaqus ​​​​​​​