Here's how DC handled reboots/relaunches back when I was a toddler. Everything a reader needed to know about Superman and his allies could be found in this old DC house ad that ran in their comics in 1970 or 1971. For that matter, this is almost everything an imaginative writer really needs to know to craft exciting stories about Superman. A reference drawing of Lois Lane, one of the Daily Planet, that old bit about his being "rocketed to earth from the doomed planet Krypton" and adopted by a farm couple and you're off and running. Give Superman a new personality, invent crazy situations and relationships we haven't seen before. Give flight to your wildest imaginings about what this near-god with a human soul might experience and do.
You don't need a 12-issue crossover series with some prologue and epilogue miniseries bookeending it or a lot of press conferences. You just run a house ad: "Superman was like this; now he's like this. Have fun!"