Personaly because I like to see chips fly, I would get one of those 5 flute 3/4" cutters and goto town.
or a 3/4" gar 3 flute alum cutting endmill run it at 10-12k and 150+ IPM
if you have a cad system you can use a face mill and hog the crap out of it, thats always fun to watch, Ive done it on big cut outs with the 45 degree insert 3" face mills, If I needed to do it again I would buy one of those 90 degree ones.
then after the face mill clean it uo with a 3/4" endmill.
10" dia is alot of stock to remove, bigger the tool the faster will with run.
but in reality:
I have cut out slugs so to speak, using a 3/4" endmill leaving .100 on the depth and .100 on the ID, then took a 1/2" endmill to break it out.
Never use the same endmill size to break the slug out as it tends to snap your endmills unless you both the slug to be cut out to the table before cutting.
9" dia 1" thick material is a good chuck of material to salvage and not cut it up, so I would go that way myself. you will need a sub plate as well so you dont cut into the table.