That looks tricky to get off mate,
without removing a little wood to allow that longer than wide, un-slotted "Head" to unwind .That screw has to be turn out somehoo.HHmmm!
Perhaps remove as little wood as possible,lightly slot the screw remove.Then you could drill out for a matching wooden plug to seat the head,after its been rounded up & slotted.Then I guess you'd have to file & sand everthing to a pleasing shape & contour .
Or just work around the damn insert smile!!
good luck
franc