Transfers require the agreement of three parties to happen; buying club, selling club and player.
If two of them push hard, it's normally enough to force through a deal - unless the third side of the triangle happens to be Daniel Levy, as Harry Kane and Manchester City have found to their cost.
It's rare a player of Kane's stature is kept at a club kicking and screaming against their will. Even Cristiano Ronaldo, Luis Suarez and Tottenham's Luka Modric finally forced their way out 12 months after being denied their moves.