Stand looks like it's made out of Pine. Most mass-produced ones are built with staples.
If so you may see them installed from the inside.
As already suggested, get the new and old sumps ready for the swap, then drain the tank as low as will allow your fish to still swim. That top rail is probably not strong enough to support the full weight of your filled tank.
Although I've seen people place tanks on just a couple stacks of bricks with no center support, why risk it ??
I like the idea of taking it out through an end without cutting any of the top/bottom rails over removing the center brace.
No offence but, if you're not certain how to remove it to begin with, maybe you could find someone close by who is very handy, has the proper tools and will re-install it properly.