Dr. Dwayne
Self proclaimed tagline king.
It would generally be written into the sale agreement. If the Glazers end up holding 25% or something, Ratcliffe couldn't just disregard the agreement and purge them. (Well, there are mechanisms that allow it, but generally he wouldn't/ wouldnt need to)
He doesn't need to purge the Glazers. There are only half of the current board of 12 directors. In the event he gains control some directors will likely leave. Ratcliffe can then leverage his controlling stake to appoint or nominate new board members that will vote with him over the Glazers. This is assuming that the Glazers will for some reason vehemently oppose everything Ratcliffe wants to do having just sold control of the club to him. Weird but ok, I guess.