Hello Billhealy and welcome to the forum. Lots of great information here along with a lot of great people.
I moved your post to its own thread.
I am pretty sure that the switch just pops out. You will need a small screwdriver to do it.
How did you determine that it is the switch that is the problem?
Did you check for voltage at both sides of the heating element?
Have you checked the hi/low cutoff sensors?
Here is a link to our water heater user guide found in the 'Tools' menu at the top of the page.
It may be helpful.
Peace
Dave