Are you talking about inside or the exterior of the guitar? McIntyre’s were sold with a double-stick tape, and were often simply stuck on the face of the soundboard. But I am guessing you are talking about the underside of the soundboard, inside the box, as you mention the bridgeplate.
If it was pressed in place using the supplied tape, it is entirely possible for it to be removed by hand, without any tools needed. Then again, it could be glued in place with an advanced aerospace formulation that requires complete disassembly of the instrument in order to get at. Just kidding. It is rarely that bad.
With the strings removed, if you can get your forearm into the soundhole and contort your wrist sufficiently to get your thumb and one or two fingers (fingernails) around the pickup, test its grip by attempting to peel one side up and off of the bridgeplate, then the other. If you can feel any movement at all (in the pickup, not the guitar), and assuming you can maintain feeling in your hand for any length of time in this awkward position, you can proceed with a modicum of confidence that the pickup will come loose without tearing of the wood.
If it will NOT move, no how, no way, and you have really tried to pry it off, then it has likely been glued on. I use a modified bullnose plane for such tasks, like when removing K&K pickups attached with CA glue, for example. A plane blade lets me force the pickup (or whatever I am trying to remove) up and away from the bridgeplate (or soundboard) while pushing against the very surface I am prying the thing away from.
StewMac has a cool tool built just for the task,
https://www.stewmac.com/luthier-too...tools-for-bridges/stewmac-bridge-plate-chisel