To clean a baking pan fill a sink with some warm water and then add some dish soap to the water.
Next place the baking pan into the soapy water and allow it to soak for a few minutes or longer if it has any hard to remove food residue on it.
Then use a scrub brush or sponge and scrub the baking pan clean while it's submerged in the soapy water in the sink.
After you've scrubbed the baking pan clean you can then run cold water over the baking pan to rinse the food residue and other grime from the baking pan and rinse the baking pan until all the soap is off of it.
If it's still smelling soapy you should rinse it again or even soak it in some plain water for awhile and then rinse it again.
If you have really stubborn food residue or other grime or grease or oils on the baking pan you can also sprinkle some baking soda into the baking pan and then pour some vinegar onto the baking soda.
The baking soda will then react with the vinegar and start to fizz which will help to lift any grease, oil and food residue or burn foods from the baking pan.
Then you can rinse the baking pan under some cold water to clean off the vinegar and baking soda and other food residue.
If you have some food residue or burnt on grease on the baking pan you can gently use a razor blade scraper to remove the residue or burnt on grease.
If it's a metal baking pan be sure to dry the baking pan thoroughly to prevent it from rusting out.