Hi lee, welcome to MoI!

> How can I clean up this circle leftover from a boolean join after
> deleting the face (sphere).

It's a bit of an involved process, but you can do that by a process of using Edit/Separate to break the object into individual surfaces, then select edges that you want to preserve, use Copy to copy those edges, then use Delete to "untrim" the surface and recover the underlying surface, then paste in the edges you copied and re-trim the surface.

It's a lot easier when the cut you want to remove is in the middle of a surface where you can just untrim it and you're done - with it intersecting the outer boundary of the surface like you have there you're likely going to need to re-trim it afterwards.

There is some additional information and some illustrations for untrimming on this post: http://moi3d.com/forum/index.php?webtag=MOI&msg=444.4

And a more detailed tutorial on object repair techniques here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=446.17

The second one is more of what you'll have to do in this case.

If you'd like to upload the model here I can repair it for you if you want.


> Also, is there a way to join two objects at the seam and still be
> able to fillet? I haven't had any luck with this even with the
> centers snapped perfect. Thanks

Could you post the model for this one so I can take a look? It is hard to know what the problem could be on this one by just looking at the screenshot. You're probably just running into a bug in filleting but it may be fixed in v2.

- Michael