Not at all. Never rototill in preparation for turf. Three years later you'll have the bumpiest lawn in the neighborhood. It never settles evenly.

Just hoe or scrape it off.

Why is the grass dead? If you don't fix the problem it will die again. Is shade an issue? Watering? Flooding?

You do not need to remove the base of the grass and expose bare soil for re-planting.If raking with a leaf rake will get the dead blades to stand, rake and then scalp the area with your mower. Take care that you don't ground the mower blade.
If that won't work, an alternative is to rent a power vertical rake or just do it manually as previously recommended.

Thanks both for the replies. The large dead area was inadvertently killed with Roundup when an unexpected wind shift came up as I was murdering some weeds along the edge of the lawn last year. I expect the Roundup is no longer viable now.

The rake-and-mow-short suggestion will not work here, also I think I would then have a ridge where the new turf ends and the existing lawn still shows.

Were I to rototill the area, of course it would need to be treated as a new installation, with grading, raking and rolling to establish smooth and flowing contours while maintaining drainage.

Maybe I'll go to my friendly local rental store to see what sort of weapons the can arm me with.

You sound like a Tim Allen sort of guy. :)

As long as you don't compare me to Bob Vealchop, er, Vila from This Old House.