A good sized trash pump will drain a pond that size in a day or two at most, but you must select a pump that has the capability of pushing water the elevation of the deepest part of the pond to where the outlet is as the elevation increases as the pond drains.
If you don't mind the wait, you can also siphon it out with cheap vinyl water tube (1" or greater) as long as you have an output elevation to drain to lower than the deepest point you want to drain from. The only thing is you will need to create some means to prevent the inlet from clogging up, especially with the siphon. As the water level lowers, the force of suction similarly will decrease which means even simple debris like leaves will clog it up.