You’ve got a few options for deep cleaning your coffee maker. There are some commercial coffee maker cleaners available, but if you prefer a DIY method, you can use any of the alternative cleaners listed above.
For example, if you choose to use baking soda, start by filling the water reservoir of the machine with a baking soda/water solution. Then, activate the coffee maker's brew cycle and allow the cycle to brew halfway through. Then, stop brewing and let the rest of the mixture steep in the reservoir for 30 minutes to 1 hour. Then, finish the brewing cycle.
Whatever cleaner you choose, just make sure to brew clean water once or twice afterward to eliminate any residual cleaning agents.