There is only really one thing to learn about how to remove bike pedals and that is that each pedal has an opposite thread on the axle. The reason for this is so that as you are pedalling, one of them doesn't fall off, which it would do if both pedals had a standard thread. So with that in mind, how do we know which is which?
The left hand (non-drive side) pedal has a left hand thread meaning the axle should be turned the opposite way to normal to loosen it (clockwise). The right hand (drive side) pedal has a standard right hand thread on it, so loosen it the way you would with almost all other bolts (anti-clockwise).
In terms of tools for the job, usually only a pedal spanner or an Allen or hex key are required to remove the pedals. Some pedals don't have a flat section on the axle for a spanner, so pay attention to which tool is required.
When refitting your pedals, some suitable grease should be applied to the threads on the pedal axle, to ensure they come off without issue if you need to remove them again.