You can use the Edit Mesh toolset in the Mesh module to improve the mesh quality. You can modify an orphan mesh, or you can modify an Abaqus native mesh.
What can I do with the Edit Mesh toolset? What is the difference between editing an orphan mesh, a meshed part, and a meshed part instance in the assembly? Meshing strategies and mesh editing techniques Using the mesh editing tools Editing nodes Editing elements Editing the entire mesh Editing and refining an orphan mesh Undoing or redoing a change in the Edit Mesh toolset