On Friday, December 1, 2017 at 8:44:53 PM UTC-6, wrote:
I dont know if anyone actually discusses home repair on this group
since it's mostly all politics now, but if anyone happens to still
discuss the intended topic, I am looking for some advice about
replacing the floor around my toilet. The floor was made of particle
board and it's gotten bad. I need to replace it around the toilet. The
toilet is loose and has been a little crooked for a long time now.

I know how to remove the toilet, but I am not sure how to fit the
floor around the flange. I plan to use treated 3/4" plywood for the
replacement. The problem is that I have always seen the flange sits ON
TOP of the floor. The plumbing is PVC so I assume the flange is glued
to the pipe. I know that can not be separated.

So, how do I get the flange ON TOP of the floor? The only thing I can
think, is to install it in halves and shove it under the flange. I
suppose this would work, but I'd like to avoid having a seam in the
plywood right under the toilet, especially since I cant add some 2x4
framing under it, with the flange in the middle.

Is there another way to do this?

It appears that you have it figured out but you should use treated 2X4 lumber under the treated plywood halves. Something to seal the seam and any gaps in the repair might also be a good idea. ^_^

[8~{} Uncle Toilet Monster