Cooling a printed object, still on the build plate, briefly in the refrigerator or freezer may make it easier to remove from the build plate. Check that your object won’t bump the print head when you remove the build plate from the printer: slide the build plate forward, and if necessary raise the print head to leave plenty of room above your printed object; the “Raise Print Head” button on the printer local web interface “Manual Printer Controls” screen may be helpful. Then remove the build plate, with freshly printed object still attached, from the 3D printer and place it in the refrigerator or freezer: four or five minutes in the freezer may suffice; ten to fifteen minutes is usually plenty.
If you have used a layer of (water soluble) hair spray on the build plate to create an adhesive surface, soaking the build plate (with object still attached) in water should loosen up the hair spray enough to easily remove the object.
A spatula may be useful to aid in removing objects from the build plate. But use the spatula gently (so as not to break the build plate)! You should not have to “pry” or “force” the object.
Note that while an object may be less “stuck” to the build plate while still slightly warm, delicate or fragile details may benefit from thorough cooling before you attempt to remove an object.
For some objects, printing with a raft may better allow removal from the build plate without damage to the bottom of the object.
For a video discussion of removing objects from the build plate, see:
Polar 3d youtube video “WWBD - Removing Print from Plate
After removing an object, check whether it is time to clean the build plate and/or apply more hair spray (or other adhesion aid).