Try dropping the distribution database via the cleanup sp, this effectively runs the menu command 'Remove Publishing and Distribution' but bypasses the checking. Run

USE master

GO

EXEC sp_dropdistributor @no_checks = 1

GO

You should then be able to rename your SQL server with

EXEC sp_dropserver ''

GO

EXEC sp_addserver '', 'local'

GO

but don't forget to restart the services or it won't take effect.