Cant get my 50 gal rheem electric water heater to drain to change elements

There is 2 ways to do this.
The first way is to turn off the power. Turn off the incoming water (cold) to the heater. Go to a faucet close to the location. Turn off the cold water supply under the sink. Open the hot water side of the faucet. Allow any water to drain from the faucet. Make sure that the water coming out is not under pressure. You should be able to tell by how it come out. Easy, or forceful. Now go to the heater and open the bottom drain valve. The reason it does not drain very easy is because you have a vacuum. Similar to having a soda bottle full of water and turning it upside down. It will drain but it will "Glug" and drain slow. Opening the hot side of the faucet relieves the vacuum and it should drain o.k. When you are done with your repair, leave the hot side of the faucet open and turn on the incoming water to the heater on. Let it fill till you get a steady stream of water from the faucet. This "Burbs" all air out and ensures the tank is full prior to turning on the power. When you get the steady stream, turn off the faucet and restore power. In some cases, the heater may sweat because you are heating very cold water. This is normal and will only happen this one time.
Now if you want to know the second way, let me know. I've done it dozens of times with plenty of success and minimal mess.
Good Luck