[Bonanza]

If the Bermuda grass is spotty, the only way I can think of to get rid of it is to either:

Dig it out a little beyond the spot where you see it, OR

Kill the area with an herbicide, also somewhat beyond its growing area.

Then replace the spot with a new piece of sod.
Make sure you wait about two weeks so that you can tell if all the Bermuda is gone.